True, the two "communities" are rather isolated (whether purposefully or not I don't know) from each other - by this I specifically mean the forum/site that players use to communicate with each other. If the two communities weren't isolated, we would be sharing the same site and forum as well. The main things that we share in common include the port (in this case, versions 98d & 98e of Skulltag) and the master server.
The fact is that there is a possibility that some players frequently play both MM8BDM and other mods, but many players may not as well. The question we must all answer is whether or not the two communities are meant to be separated from each other or merged together. Then a decision can be made regarding whether or not MM8BDM's community deserves its own master server as well as its own site and forum, or if it could viably survive together sharing the same master server as Zandronum.
EDIT: I'm not too sure, but I think one of
ZandroNet's intentions was to give a filtering option so that people could play whatever mod(s) they choose and to filter out other servers with ease. It also appears that IDE already has such a feature.