it seems to only have 5 topics, why so little

by the way if it has so little why does beth, keep it up

The Quake community already had many well-established forums before these were opened and I expect most people in those communities don't see a reason to migrate. If you have a good forum with a good group of people there's no reason to abandon it just to be somewhere official. It's also been a while since a brand new Quake title has been released and while the IP has hardly been fallow it's the big releases that attract the most attention - Quake Live looks neat but I picked up Quake 3 when it was released.

These forums may not be terribly active now but that's no reason to shut them down.