Curation projects are, to me, inevitable anyway. Humans have a natural tendency to centralize. Historically; family -->tribe-->village -->city -->nation --> blocs of nations (the EU) and people now speak of world governments.

Internet did the same thing, where the vast majority of internet use is centralised around a few company's apps.

Simply put - because it's easier. I see curation groups as representatives for people who support that given cause. Much like an MP or something.

Whether or not you think this is a positive or negative thing, it's gonna happen regardless