As time goes on, the world’s poorest - those who live below the World Bank’s extreme poverty line of $2.15 a day - are increasingly concentrated not in stable countries, but in unstable ones.
Without stabilizing fragile states, all our progress at reducing global poverty will soon stall out, leaving hundreds of millions living on less than $2 a day.
I haven't seen a lot of evidence on other kinds of peacekeepers, so I don't know that I can say with confidence how effective they are! I would guess it depends on how much they are seen as a neutral third party.