I don't want to pile on because I havn't seen that particular thread. I tend to stay out of "folk definition" threads- because I just don't care. But from experience I'm going to guess that the parties were from England. I'm not sure why this subject is of earth shattering importance over there but it seems to be that way.

Now is bluegrass really bluegrass if it doesn't have a banjo? That's something you can really sink your teeth into. YMMV.