The one thing I learned from hosting superkuhbitj6tul.onion (from a home computer) for ham radio and science stuff for about a decade was that EVERYTHING ON A .ONION IS EPHEMERAL. When the tor project correctly decided that for high security torv2 no longer was anonymous enough they unilaterally wiped out every torv2 .onion site that existed. Every link that was made between these sites came to an end in 2021 when they released a tor client without support for torv2 onions and tore the web to pieces.

Know this: the "dark web" is not for people who just want to own your domain name. It's for SECURITY and that use case is going to drive all their decisions. And if it wipes out every community in the entire tor dark web? So be it. And they'll do it again. Don't build your communities on the sand that is the dark web. You won't like the result.

You're not wrong about significant brittleness and lack of sovereignty (and the same should be said about the web, too, roughly speaking), but I don't think your prescription is correct. Thus far, my only solution has been to maintain a variety of gateways to the same signed object which itself provides the evolving list of connection gateways. Gotta stay ahead of the whackamole through diversity, imho. Ironically, I've found my i2p and tor identities have been some of the longest lasting, especially compared to non-bigcorpo clearnet web hosts. That's definitely not how most people want to use the net, ofc, but it's probably the right kind of practice that we should collectively be engaged in together if we want communities that actually own the means of production about as far as we reasonably can atm. And, these days, LLMs make this process much, much easier, too, as rediscovery and rebuilding custom infra per individual or community is far more doable for the average person (if they really wanted to do it, and I'm not claiming they would*) these days.

Don't tie anything to a domain name you mean. Advice that's just as valid for clearnet.

v2 onions being deprecated was announced long in advance so many sites managed their transfer by announced the new URL well in advance. I don't think anyone was really bothered.