So because Facebook, tiktok, YouTube et al start over-censoring, people just think fuck it and start hosting their own content again?
The UK police love to go after "soft" targets and there's no-one softer than someone who's life can immediately be ruined by arresting them and thus getting them fired due to missing work.
Edit: I now see you mean "host their own personal content" but the point still stands.
Big white-collar crime is a different, and much more resource-intensive, set of challenges to investigate and prosecute. As such, it is not a constabulary remit - it needs bodies such as the SFO, which depend on extensive budgets to be effective. Blame the government for not prosecuting the big white-collar fish.
I'm sure it grinds every copper's gears that the bastards get away with it.
Very few people outside a small clique want or care about self-hosting anything.
Something like Twitter cannot be as easily replicated, but it's never been about privacy ad encryption.
Another thing that's hard to replicate is a global namespace. Federated namespaces (see email. mastodon. matrix) work acceptably well though.