Aren't admins already able to defederate, which is essentially, a fediblock?
Lemmy
Everything about Lemmy; bugs, gripes, praises, and advocacy.
For discussion about the lemmy.ml instance, go to !meta@lemmy.ml.
I know Matrix instances use common ban lists as well. So if the matrix.org instance bans someone, it usually also means being automatically banned on a lot of other instances who follow matrix.org's ban lists. A system like this might be useful alongside a wiki documenting bans.
So basically centralized cenzorship for decentralized Fediverse?
Well notbexactly. Just a faster way to stop spam. Block must be motivated of course, and each instance decides per se
Going through suggested lists I can count the instances that have the reason "spam" on my fingers, doesn't seem to be actually useful (or intended to be) against spam