To elaborate on what I was hinting at: the moment you introduce a word like 'abuse', you need concrete policies for detecting it and concrete penalties. Otherwise you risk turning into a site that has some amount of arbitrariness and turns away some people. (Sound familiar? ^_^)
True, but people seem to like curation. Especially when they themselves get to do the curating.
One interesting thing about laarc is that there hasn't been any abusive behavior whatsoever. This will certainly change, but when? The community has been so amazing that it might be ok just to trust people to be good. If people show up and start spamming, it'd be pretty obvious.
You're right that there should be clear procedures for handling situations like that. If a restriction is placed on a user's account, I'll make sure they know why it happened and how to resolve it. But it's in a spirit of cooperation, not judgement.