I was thinking of this but I only really mess around with stuff like leetcode at most, but even then you just end up having to filter just as many other communities manually which is basically the same problem in reverse. Also this is an issue with getting many instances loaded up on a single small one, but how do you populate your small instance on a hundred different instances?
I think the most sensible solution to all of this would be an improvement of the communities directory, although if you wanted a dumb quick universal solution just having said bot operating in the background on all instances as default would solve it.
Open the instance
Scroll to the bottom
Click “Instances” in the footer
CTFL + “Blocked” to take you to the defed list