> There aren't any decentralized alternatives to Facebook, Google, or Twitter because nobody's been able to ship one.
This makes it sound like a technical problem, but it's also at least partially a market problem. It's much more straightforward to squeeze revenue streams out of centralized walled gardens like these than decentralized equivalents.
True, but this is at least partly balanced by the fact that decentralized systems cost considerably less to operate. With my own example, I've already calculated that I could handle over a million concurrent users on a few hundred a month in hosting costs. If I had to relay all that bandwidth it might be hundreds of thousands in costs.
A decentralized Facebook would have less revenue, but also negligible hosting costs.
This makes it sound like a technical problem, but it's also at least partially a market problem. It's much more straightforward to squeeze revenue streams out of centralized walled gardens like these than decentralized equivalents.