The SA community isn't another Dom3 community, it's a gaming community in general, same for QT3 and the OO crowd. (Something Awful, Quarter to Three, Octopus Overlords) I started off at the latter before moving to here, too.
I do hate extremely big all-purpose threads for games like they seem to do it at those sites, though, too. They have threads with over 60 pages about Dom3 or Dwarf Fortress etc. and EVERYTHING about that game is being posted in there. That might support their discussion board structure that everything about a specific game is in there, but like KO wrote it's totally impossible for an outsider to keep on track about what's going on in there if you just decide to jump into the middle of it. Lots of good and interesting posts might just drown in there.
EDIT: Forget a mere 60 pages, apparently they're over 180 pages right now at QT3.