I'll only add two things.
First, its not really hard to join an game, regardless of Mods used. There are plenty of Vanilla games, CBM games or Awesome-Mod games.
(At the moment I'm in 3 Awesome, 2 CBM and 2 Vanilla games)
Second, there are Nation-Mods. But those get a little less exposure in MP.
The Cataclysm and Randomocalypse mods are a special subset of Nation-Mods.
Lllamabeast made two Combi-Mods with a
few Nations
http://z7.invisionfree.com/Dom3mods/...?showtopic=379