I can't say I agree. Most other sites I've ever been (even moderated myself) on don't have the 6 month thing, it's just a permanent record with maybe a bit of moderator-discretion.
Notable posters might well be at odds with people more, but that's no excuse for acting like an idiot. I don't understand lashing out in forum posts, it's not like a face to face conversation where you just blurt stuff out. You have to type things through and read them, it's not really an impulsive thing. Whilst I'm not the most controversial person usually, I've gotten into my fair share of disagreements and I have quite a few posts, and still I've only ever gotten two warnings, one of which is very old.
Having different opinions has no bearing on your conduct, it's perfectly possible to disagree without being a total arse about it, especially if it's not your first offence. If you're not going to bother trying to improve them you get what's coming.
I get that it's sad to see users you recognise go, but I'd be more annoyed if people were getting special exceptions. I think Sky said in a thread the other day that they were actually getting quite a lot of people complaining as to why Vault hadn't gotten in more trouble, and there was a lot of anger when she was actually banned. There's no way that the mods are going to please everyone, it's a pretty impossible position to be in, I sympathise a lot. They get a lot of stick for doing what they do, I don't really feel it's deserved. A lot of it just comes from differences of judgement, usually I can't really fault them for it.
