Yeah a lot of those were communities that just appeared out of nowhere and spammed my All suddenly - which was likely just one person trying to get the ball rolling with a topic I'm not interested in. Whether that initial wave of content ended up attracting an active community vs just fizzling out, idk, but a good chunk of them are probably ghost communities now.

Another good chunk are redundant communities - like 5 or 6 if those blocks are some variant of "To my badass hero" which is the same poster that keeps making new communities for softcore black and white porn... I can only assume in effort to circumvent blocks like mine.

The number of real/active communities on my blocklist is probably closer to a couple hundred - the rest of just the result of content whack-a-mole to clean up short term messes.