P2P is probably better for direct communication, but I hardly see how a P2P publishing platform (forum, microblogging, ...) would work. As far as I understand, this would involve a permanently running home server storing at least your full history, right?
Add in you are at the mercy of your home server, you can lose your account have it immitated, and more.
Indeed, the main criterion to choose an instance (server) should be that you trust the people who run it. If no existing instance fit that criterion (or any other of your criteria, for that matter), you are free to create one.
Great yes you may find one that suites you better, but users now can end up isolated to their island
... which is also a criterion to look for an instance (server). Some look for a broadly federated network, others for a "safe space" kind of experience. Servers exist for both use-cases.
but now you are isolated for the previous island and maybe other
which makes sense when one considers moderation. If you are running a "safe space" instance, you don't probably don't want your users to be exposed to less moderated content, and you certainly cannot moderate one by one all the sensible content from across the federation. So it makes perfect sense to federate only with instances who have a reasonable code of conduct.
You either have to run multiple accounts or accept the limits.
Note that there's another solution allowed by the following property: an instance can be federated with two instances who are not federated with each other. Concretely, this means that you can create an instance who both has a CoC for its own content strict enough to federate with safe space ones, and federates with instances who have a less strict CoC to access their content.