Someone has to pay for them, and all the other infrastructure around them. And with a large part of the world being on the internet a significant portion of their day the costs for even the most efficient centralized services running "at scale" (see: hundreds of millions MAU) are astronomical. In the tens of millions to hundreds of millions of $ annually, just an infrastructure, never mind human resources.

Almost none of these companies survive off of donations. Wikipedia stands out as one that does mainly because they host static content, which is incredibly cost efficient to serve up., and even then their costs are pretty astronomical (there are some debates around their costs of course).

Federated services have an asymmetric scaling problem. A linear growth in users results in a exponential growth in infrastructure costs. While centralized services tend to be almost the entire opposite of that and usually see logarithmic infrastructure costs against linear user growth. Where infrastructure costs are more efficient as their user base grows.

Federated services don't benefit from running at scale, the more they scale up the less benefit there is to scaling. It's a really shit situation to be in.

This is why the internet is largely just cyber feudalism. Because the only ones that can afford to host large scaled services for their users are the ones that are making money off of it. And that's for centralized services, never mind decentralized services which are unbelievably more expensive to host.

I'm coming at this from the standpoint of an engineer, I don't have answers or solutions, but the first thing we have to do in order to start figuring out solutions is to recognize the problem.