The fact that you don't like them doesn't mean they should disappear. The fact that they're still a thing means people like them.
Part of the problem is that there are far too many of the type of people who like them.
The issue is that they aren't in any way destroying other servers. If you don't like knife TDM players and you don't like knife TDMs then you why aren't you happy that the knife TDM players are on the knife TDMs and not near you? Even if they are taking away a chunk of the populace that you want to be elsewhere, it's THEIR CHOICE.
The only course of action left is to leave them alone.
Hmmm..
I can think of one solution: Awareness. Point out that there are a helluva lot better servers, give some examples, then leave the knife TDM. Anyone else who is intelligent will leave with you, leaving all the morons sequestered in their own little server, so that you don't have to deal with them screwing up the game everywhere else.