I don't think bans are given out for providing such services. Even if they could, your logic still wouldn't work here because they're huge account farmers and it really doesn't make a difference if one of their accounts get banned. Negative rating will stand as a warning for projects who hire these ANN bumpers that by using such services you're risking your project' future on bitcointalk.
The reason of my suggestion to give them a temp ban is this:
Sending unsolicited PMs, including but not limited to advertising and flood, is not allowed.
About hiring them: You think those who hire them really do care about their (ANN bumpers) reputation. They will hire the ANN bumpers just to bump their topics.
The ban would make the most sense strictly looking at the PM's. I recall
Hhampuz received a 7 day ban when they sent some PM's out soliciting business. Wasn't a big deal and they just didn't do it again. You will see there was no need to neg rate him for the PM's.
With tags that's again up to each person to decide based on this servic that they are selling. I have seen people leave negative feedback in the past with thread bumping services - not sure if they've changed them. They took issue with the nature of the service, itself and found it untrustworthy.
Since this service is aginst forum rules so it's not matter of just tag.
Not sure who gave you this idea,
Maybe I misunderstood but I believe coolcryptovator is saying that leaving feedback isn't necessary and allow admins to take action for breaking forum rules.
theymos has stated when you see someone breaking "guidelines" that you should report them and let the Admins take action.
