I don't recommend the public-facing website. Their journal is higher-quality and tends to focus more on longer-term strategic questions / analysis, although there's still a lot of variance. Older issues are pay-walled but I believe articles are open-access for a short time when published.
I find the broad proposal of quantifying impact in an equity-like form and providing that "impact equity" to contributing stakeholders proportionally to their contribution to the organization's impact in an attempt to improve the efficiency of the matching market between organizations and donors compelling. I also think it may have several second-order effects, of which some may be positive and some may be negative, which merit consideration.
More efficient matching markets between organizations and donors
It seems plausible that quantizable impact equity would substantially simplify the donor coordination problem and reduce the communication complexity involved in charity spending decisions. As I understand your proposal, that simplification will result from the distillation of the charity's program options into a single (or perhaps several, since there may be threshold effects in implementing particular programs) impact equity offers, which can then be evaluated by donors on a comparative basis to other impact equity offers they have from other charities. Charities then need not spend time proposing particular programs to individual donors, and donors needn't understand the details of the particular programs the charity might pursue.
Less clear to me is how comparable impact equity of different charities would be - would there be a specific metric (e.g. estimated QALYs saved) or would donors construct individual conversion rates (at least implicitly) based on their evaluations of how effective charities are likely to be over their lifetimes? The former further simplifies the evaluation complexity for donors but might be hard to evaluate for many kinds of programs and could lead to problematic incentives (if donor decisions are being made somewhat automatically, charities which overestimate their QALYs saved will have an advantage), while the latter might be harder for a donor to understand or estimate than the impact of a specific program (although this may vary widely based on the charity). This is different than venture capital investing, where the input investment into and eventual expected returns of all potential companies are in the same currency.
Alterations of donor incentives
The reification of contributions into measurable impact equity could lead to a more competitive game between donors since this impact equity confers a measurable kind of status which can easily be publicly displayed. This might have strong positive effects - since the status gained in return is more valuable, donors might donate more - concretely, imagine if everyone's "impact score" were displayed beside their forum profile or Twitter account. Measurable impact equity might also lead to perverse incentives to overestimate impact, depending on how impact equity from different organisations is compared (see above paragraph).
If the impact return curve of charities is some kind of power law, impact equity might cause donors to contribute smaller amounts to many newer organisations in the expectation that most will fail to have much impact but one or two will succeed and "return the fund". I don't know enough about the current funding landscape to judge whether newer organisations are currently over-funded or under-funded.
Alterations of employee incentives
Impact equity could be given to donors only, or given to donors and organisation employees. The latter is the closest to the for-profit equity model, where the founders start with all of the equity and then parcel it out to employees and investors in recompense for work or capital. Giving impact equity to employees might have positive effects - as for donors, it is tangible status and might encourage more employees to join the organisation or encourage existing employees to work harder to increase the future impact of the organisation (and thus the value of their impact equity). However, it might also lead to discontent if employees don't consider the impact equity allocations to be fair (whether between different employees, between employees and founders, or between employees and investors). One other advantage of not quantizing the individual contributions of employees is that they can sum up to more than 100% - all twenty employees of an organisation may each believe that they are responsible for at least 10% of its success, which is mathematically inconsistent but may be a useful fiction (and in some sense it could be true - there may be threshold effects such that if any individual employee left the impact of the organisation would actually be 10% worse) - if impact equity is explicitly parceled out, everyone's fractions will sum to 1.
Thanks for the write-up. I think historical examples can be helpful in understanding the nature of current social tendencies, but I also think it is important to precisely analyse the possible deleterious impacts of de-platforming or "cancel culture", which differ substantially from the analogous occurrences you cite in the Cultural Revolution. In particular, I think it is necessary to distinguish between the first-order effects, which I think are not very severe, and the second-order or third-order effects, which are more concerning.
By first-order effects, I refer to the instances you cite of cancellation-for-cultural-heresy.
First, the immediate stakes are far lower - in the Cultural Revolution, "counter-revolutionary revisionists" were sent cross-country to re-education camps, tortured, killed, even eaten. As far as I am aware, none of these things have happened recently in America to public figures (or made-public-by-Twitter figures) as a result of the sort of backlash you discuss.
Second, the scale of the first-order effects, although difficult to precisely ascertain, probably appears to be much larger than it actually is due to availability selection effects (similar selection effects to those which lead to scope insensitivity in e.g. videos of deaths from police brutality as opposed to deaths from coronavirus). Particularly egregious cases of cancellation - which certainly exist (such as the case of citing detailed studies on police brutality by race you mentioned) - are probably pretty rare on the whole, just as particularly egregious cases of police brutality are pretty rare on the whole. Both, of course (and far more the latter), are concerning when they do occur, but they should be considered in context, and one has to be very careful as an observer to understand the selection effects at play.
Third, at the moment, this cultural movement (whatever you want to call it) is not orchestrated top-down or directly backed by the formal structures of power (legislative, executive, and judicial branches of American government, and the military), in stark contrast to the Cultural Revolution. Unless this changes (which is possible), I think this makes violent conflict quite unlikely (also for the reasons of interdependence between urban/rural areas that you cite), and it means that constitutional protections (although under threat for other reasons) are not directly at risk for reasons of "cultural heresy".
For these reasons, I think the first-order effects are not that concerning, and the comparison to the horrors of the Cultural Revolution on that basis is not particularly well-founded.
I think the higher-order effects are more serious.
First, cancellation-for-heresy can create a "chilling effect" where intellectuals and public figures are unwilling to voice their true opinions for fear of being accused of heresy and losing their jobs or reputations. Fixing the underlying problems - whatever the particulars - requires a dispassionate analysis of the facts of the matter, and an appreciation for the real scale of particular problems independent of availability heuristics - so the "chilling effect" may actually achieve the opposite of its nominal intent and prevent people who would have otherwise been e.g. doing research into evidence-based police reform strategies from doing so, and thus prevent the results of that research from being enacted into policy.
Second, the contortions induced by conformity to this kind of pressure, e.g. the about-face of many health professionals and public figures on the coronavirus dangers posed by Black Lives Matter protests vs. Trump rallies, whatever their private views may have been, have potentially serious consequences both to immediate behaviour (COVID19 will spread at a protest without regard to the political motivations of its attendees), and to public trust in institutions, already at a low point and continuing to fall. Considering the current US coronavirus death toll, I think these kinds of second- and third-order consequences (although certainly not solely a result of this cultural phenomenon) are much more concerning than the immediate first-order consequences of "cancellation" or the like.