I think the bigger problem is cross-generational power. YC itself is somewhat terrifying in this regard, but that's a different topic. In regards to Google and FB, even if we like Google now, we probably won't like the Google 60 years from now. But what is there to do?
Google stopped Microsoft by making Microsoft irrelevant, in the "Microsoft is Dead" sense: Nobody is afraid of them anymore. But people fear Google and FB. Imagine a Microsoft competitor to your startup vs a Google or FB competitor.
This could be a lack of imagination, but it's very difficult to imagine some new company making Google or FB irrelevant in the same way they made their predecessors irrelevant. Think of oil fields. At one point, before oil fields were monopolized, I've heard the ecosystem seemed pretty similar to Silicon Valley circa 2008. Everybody seemed to be able to get a slice of the action, and while it took determination and luck to get involved, it was possible.
Now the oil industry is on lockdown. Imagine asking "What are we doing about Exxon Mobil?" or Walmart. You can't do a damn thing, and there's no shame in admitting that.
As defeatist as it is, we may want to start thinking about ways of riding out the next 40 years in a productive fashion. It's more beneficial to say: Ok, Facebook, Google, and the closed internet are here to stay. Now what?
For example, if you're really set on doing something about it, one of the most effective things you could do is try to join the companies and shape them yourself.