Personally I think that if there was like a central link/front end to access everything and then have each user be able to have a recommended list of instances/hosts to access would be a more user friendly solution and a better solution for search engines. I know the fediverse is about decentralization but having a central front end and decentralized back end seems easier for new users. And then for the back ended hosting aspect each host would be able to manually pick which instances or communities to host and mirror. I'd like to hear your ideas since I have no idea what I'm talking about.
I think that would be useful! I also think that anyone putting that much work in should look into hosting their own server, because they've already done the hardest part of hosting a server in the fediverse. A big part of the issue is that a lot of ActivityPub apps don't really have granular enough customization baked in to support that sort of thing just yet; you can get some apps that do that on the user side, but anything on the server/community side is usually just "block all" or nothing. The admin of my Mastodon instance is always complaining that he can't just hide certain instances from the "all" tab without blocking then entirely, and he just wants to hide them so they don't overwhelm the server, not block them from showing up for people who choose to interact with them.