Although EA is trying to do the most good possible, it's likely that we've overlooked or missed some of the best opportunities to do so. I'm trying to think of examples of when this has happened, in order to better understand our blindspots as a community. As a fictitious example, if we're continually overlooking media opportunities that then have a sweeping cultural effect on society, this is worth adjusting for to make better decisions in the future.
One more fleshed out but not quite perfect example might EAs not supporting Extinction Rebellion during its incubation phase in 2018. This might not a great example for a couple of reasons:
- Whilst I think there's some evidence that Extinction Rebellion has been quite cost-effective in reducing carbon emissions, it's also not conclusive by any means. 
- There wasn't much EA grant making, if any, on climate related issues in 2018, which might actually be a larger blindspot of its own due to the increased interest in climate risks now.
- Extinction Rebellion still ended up happening and being quite successful, so the counterfactual of EA not supporting this was seemingly okay (although we have no idea about how successful it could have been with greater support early on).
Ignoring these points and assuming this example was much stronger, the case would be something like: Extinction Rebellion had significant positive impacts on reducing carbon emissions, potentially outperforming other grantees of EA funding working on climate issues, yet we failed to identify this opportunity a priori. Not only did we fail to identify this, but other charitable organisations did, which indicates they had some information or connection that the EA movement was lacking. So the question becomes, why did we overlook this opportunity, and how do we stop it happening again?
One consideration to keep in mind is that if we can think of great things happened without the EA movement, then maybe it's fine as counterfactually our support wasn't needed for these interventions. So the more interesting question might be, what could have been extremely impactful in doing good, but failed to take off at all, and the EA movement could have changed this?
I've generally been framing this around specific interventions within a cause area that we may have missed e.g. interventions that could have been extremely impactful within AI risk or Animal Welfare we overlooked. However, this could also be true for cause areas, such as EAs updating towards being more concerned about climate change in the past few years, whilst some organisations were somewhat ahead of the curve relative to us (albeit potentially for different reasons to our interests in climate tail risks). This question might be more like: Were some organisations or institutions ahead of the curve in terms of cause prioritisation relative to EA, and why do we think this was?
Plus I worked for them for 2.5 years so there's probably a case of motivated reasoning.
In the specific case of Extinction Rebellion, my somewhat uninformed prior is that as a movement, EA is generally more focused on technocratic theories of change, which focuses on persuading or working with elites, rather than more democratic or people-powered approaches.
However, there's also the case that we could have scaled them up further or initiated them earlier, which is obviously also good.