What you're basically talking about is centralization. And, as much as it has tremendous benefits of convenience, I think a lot of people here can cite their own feelings as to why that's generally bad. It's a hard call to make.

There is no way that could get abused... Like say, by hosting your own instance and banning anyone you want.

I think a ban list is, unfortunately, contrary to the notion of decentralization; as otherwise warranted as it is in this instance.

What about a centralized list of data on major offenders, which could be made subscribable by instances? Perhaps a way of calculating probability of origin, matched with offenses made by that origin in the past? That way an instance could take it under advisory, and take actions suiting them?

This is only the beginning of an idea, but if it is possible to collaborate without centralizing, we should explore it.

Soo... You want to centrelize a decentralized platform...

It might be in the works, comment

I feel like this would be difficult to enforce

We already have that, it's called prison. Can't go on the internet from Prison (at least I'd assume so, wouldn't make much sense if people could). That's not 100% since people need to be caught for it to work but once they are it certainly is.

Though other Global ban solutions don't really work well because they require a certain level of compliance that criminals aren't going to follow though with (i.e. Not commiting identity theft). They can also be abused by malicious actors to falsely ban people (especially with the whole identity theft thing).

[ptrck has been permanently banned from all social media]

Mabe FIDO for identity purposes is a good idea. Mabe some process that takes a week to calculate an identity token and an approval and rejection system for known tokens