Often times, it's used in a petulant manner, like slamming a door. It doesn't really contribute a whole lot to a conversation, and is used more like a weapon to gain attention and to stir up trouble than anything else.

Before we enforced the rule, it certainly caused problems and derailed several threads. Now that it is in effect, those problems have been minimized.

We don't enforce rules willy nilly--that just creates more work for the moderators. Usually, there are reasons behind them, like addressing an ongoing problem.

It's been posted several times in various threads, but as such, it's one of those smaller rules that is encompassed and helps enforce a larger one, such as "don't derail threads" or "flaming, baiting, trolling or otherwise inflammatory comments" rules.

Yep.

It's very rare. Other than spammers/scammers, maybe one or two a year?

Eh, a lot of times, it's a moderation warning with no eject. Thread ejects only happen when something is really over the line or if it's the same individual who keeps breaking similar rules.