"It's all about free association."
Well, as you point out we can only associate with available mechanisms. For instance Steem. Is Steem perfect? No, not at all, and in fact we can see just how broken it is today. Will what's available be perfect? No. Let's just hope it's better.
But I think the question asked was valid. Who defines better? Hopefully the community does, and increasingly so going forward. Folks with the skills to make the platforms communities will choose between can do what @dantheman and @ned did, and enable golden parachutes like the founder's stake and dooming platforms, but if more choices arise, better platforms will win the communties.
We are seeing what golden parachutes do to communities, and it ain't pretty.