Those 15 STEEM accounts are the worst excuse I've seen so far to not go after the big bad actors. They practically don't hurt anyone, except maybe a small sting to the ego. Their downvote has a value of ~0.0001$, that's not noticeable even if you get multiple downvotes from accounts like that.

I agree that steemit should undelegate them, but using that as a reason to let large scale abuse happen doesn't have any logic.