What do you mean?
He means that the players of any given mod are only a small subset of the whole community, and therefore they have access to fewer guides, less discussion, and so on.
Speaking for myself, I don't really care about getting strategy advice from other people. Developing and executing strategies is a large part of the fun of playing the game for me; so that doesn't matter to me.
-- '
Less of a community' is only really true if you're most interested in communicating about particular aspects of the game which are not shared between the modded game and unmodded game.
-- As for 'More bugs'; well, I know there is a tendency for new mod features to be accompanied by new bugs, at least for awhile; but I don't think that's an issue for the mods we're talking about in this thread. These mods have been around for a long time, and so I'm pretty sure they'd be quite stable. I can confidently say that my own mod (
K-Mod) has
far fewer bugs than unmodded game. Game stability is a top priority in my modding; and I've done a huge amount of work tracking down and fixing bugs from the original BtS code. Including fixing OOS problems in multiplayer games, crashes in the pitboss host, inconsistencies and unintuitive behaviour in the user-interface, and so on.
I can't really speak for the other mods, but I do know it's quite common for mods to include the "unofficial patch", which contains a bunch of well-known bug fixes. So, if all a mod does is use the fixes from the 'unofficial patch', and manages not to create any new bugs, then they are already doing better than the unmodded game.
So -- I feel just fine about being part of a sub-community. In my view, the community should build around the game they want to play. If the mods are better than the unmodded game, then that's where the community should go.