Something I noticed a lot is that while the whole promise if the fediverse is decentralization, it’s not sustainable and very centralized at most.
In the last months I opened multiple accounts to use multiple fediverse services(Mastodon, Pleroma, Lemmy,… etc) and I chooses non-mainstream servers to test the decentralization of the fediverse.
Most of the servers that I opened account in to use got shutdown by the servers owners due to a lot of reasons( literally every server that got shutdown has it’s own specific reason, from financials to ideology and software).
From what I can see currently at least, the best approach to social media sites are either complete P2P(which comes with it’s own disadvantages, but it has a strong advantages to consider) or one centralized server.
The problem sounds more like hobbyists trying something out and finding they don’t like it or can’t sustain it to make it bigger. It still costs money to host the servers and maintain a domain name. If the instance hosts can’t afford to keep it up or have no motivation to do so, of course they will eventually shut down, and I would expect many small instances to die after a few months because there’s no justification to keep spending money on hosting a thing barely anyone is using. Host your own if you want. Join a bigger one that actually has some kind of funding to keep going. Simply due to the fact that any random person with the time and resources can run their own servers to host the same software is what makes federated stuff resilient and nigh unkillable.
If it was centralized, if just that 1 thing died so too would the entire idea. Like putting all your eggs in one basket.