

Yes and moreover, feeds work at the community level, not individual posts. Which is a step in the right direction but you may want finer-grain control. Filters may offer more what you are looking for in that case.
I did not mention previously but PieFed also allows you to block all users from a user-specified instance, without requiring admin approval to perform full defederation. It is not perfect but it is very good and e.g. I use it to block Lemmy.ml, which saves me a lot of headaches as most of the worst, most argumentative and unfriendly (and batshit insane) comments I’ve seen come from there. Lemmy’s instance filter is horribly misnamed - it would have much better been called a community muting, as it blocks communities from that insurance but the users remain free to troll you in communities located in other instances, leaving replies, triggering notifications, etc.
The Lemmy apps Sync and Connect can also block all users from an instance.
Edit: also check out !bestoflemmy@lemmy.world - it uses cross-posts to build up a curated listing of “good” posts by some metric. Conversely, the entire instance of beehaw.org works the opposite by extensive manual curation efforts to remove “bad” content by other metrics.
Isn’t ActivityPub extremely network intensive though? If all you wanted was a single user subscribing to a handful of communities then Lemmy would be inexpensive but to pull from a lot of communities I thought people have said that it can cost a bit of money, time, etc. Also defending against attacks such as CSAM.
Maybe make a distinction then between running a “tiny personal instance with only a few niche community subscriptions” vs. a small instance, either with multiple users or even just one person subscribing to many communities, if that cost would start to become more prohibitive?