If it is not the default and automatic, then lemmy is a pointless reddit clone.
You have to filter out what you don’t want because it is not possible to undelete what has already been deleted.
Users will just circulate ready made blacklists of spammer and thoughtcriminal communities to automatically remove them all from their feed.
The alternative is that only the biggest instance and the biggest community will matter and writing everywhere else is just a exercise in pointlessness