Underrated benefit of lemmy is like minded people will tend to join the same instances and if I don't want to interact with those groups I can just filter the whole instance.
A lot less annoying then endlessly filtering content by community and user
If other instance users post on a problematic instance by accident or because there's a useful community, I wouldn't want those hidden.
Then again if it, preferably, only hides the users of the problematic instance, that doesn't really solve the core issue of bad actors being enabled in the fediverse 🤔
That's why we should use the federation features more often. You should choose an instance that federates with the instances you like. Blocking can be done on most mainstream platforms, we can defederate!
Still looking for instances that defedded with lemmy.ml...
In addition to lemmy.cafe and quokk.au and Tesseract on dubvee.org that have each defederated from it (though as Blaze mentioned they are all single-admin instances), iirc the apps Connect or Sync will let you block any custom instance you want (I don't have either, but from what people say?), or the Lemmy alternatives PieFed or Mbin likewise plus they have neat features that Lemmy lacks such as Categories of Communities.