I've always taken it for granted that Mudcat is an American site, although many users are from the UK these days. As Bill says, different people use Mudcat to discuss different topics, and some will be geographically exclusive. On the kind of things that interest me, like Child Ballads, there's a shared interest, and valuable contributions come from both sides of the Atlantic.

Personally I don't believe that being allowed to post on Mudcat is one of life's inalienable rights, and I do think that, if you want to join in somewhere like this, you just accept the rules (even if you disagree with them, or wish they were enforced more or less rigorously). No-one is obliged to provide this platform, and it does seem to me as if some people are getting very worked up about what is, in the end, just a music chat room.