The real purpose of the swear filter is not to kick all abusive players for every nasty word they say, it is just to be there.
We can all get around it fairly easily, although our filter has been coded to avoid the scun-thorpe problem, it's main purpose is just to exist.
The fact that we have a swear filter says abusive language is not allowed, it's a reminder. If I see people launching into tirades I often warn them but some times some people can be so disruptive and effect so many people it is actually worth a ban. I try to avoid it because there's too much paper work, but the problem is the whole gamer 'f u' attitude effects so many people negatively and as soon as people are upset they start driving worse and all sorts.