I’ve recently tried to use peertube and I think it could improve a lot if it showed all the content in all instances. But instead you have to look around many instances to try and find something you like. Then there’s other thing, it can’t suggest content if it doesn’t know what you like and without sharing the data between the instances it doesn’t know anything about anyone. If the user data was encrypted and shared between all sites, when you log in it could use the now decrypted user data to suggest content. Or maybe it can share the data with third parties, I don’t really know.
You can’t minimize dependence from outside servers if you want a million servers with 5 people on each.
Your subscription to a community from an outside server will always depend on the outside server providing the content from that community. And you have to also depend on your chosen server having connection with that outside server.