there was an attack on twitter by mass following with fake accounts to get the followed account suspended, only guess is there might be algos like that on relays? or apps?
Discussion
I think the thing the fake followers achieve is makes follower account less relevant for determining things like trending. It's also possible that you could get marked as spam if you're following enough accounts that are also marked as spam depending on how a client or relay chooses to determine such things. I don't believe anything like that has been implemented though.