Yeah I think it's about time to get that feature. As a user I have preferences that don't necessarily match with the defederation policies of any instance and I would very much like to choose for myself which instances I want to see.
In my case: I'm not interested in polarising, divisive, toxic content and I really don't care if it's coming from the left or from the right. But it seems to me that I have to choose a side, because some instances are blocking the right wing extremism and some blocking the stuff to the left, but not both.
Reading subscribed communities only is not an option, because then I will miss out on new stuff. And blocking all these awful communities in "all" by hand is too much work.
tl;dr not being able to block instances as a user is giving me a bad Lemmy experience
Aye