Contrast this to Facebook, which is structured specifically to prevent even large shareholders from having a say in its operations. Facebook is the Empire of Zuck, and the only factor that matters in its decisionmaking are the whims of its boy king.
I'm with you that seeing power concentrated in those places seems worse than spreading it out. But the way it looks to me now, people aren't going to generally mind their own bitcoin wallets, and will tend to use centralized brokers.
I think that's human nature, specifically some algorithm for operating in a group. If I don't feel confident doing X, maybe X is not my strong suit, and I should trade jobs with another person. If I mess up my crypto wallet, my money could almost literally disappear, so my confidence is low.
People are afraid to control their own destiny, and that's at least somewhat rational.