Well why not have an elite?
I think its a great idea to have some sessions where the quality and/or content are controlled. Makes for an evening you know you can enjoy rather than just sit through.
In sessions where you have the very good mixed in with the very bad there is little continuity and its hard to maintain the mood. Such sessions can end up spiralling downward as the better musicians drift off to more reliable sessions.
As to the genre-crashing.... its such a shame when a folk session gets taken over by mediocre pub-rockers spieling out obvious golden-oldie crowd pleasers.
If someone is going to the trouble of running a session then I can't see why they shouldn't be allowed to define its parameters.
I watched a promising "country/folk" session dwindle down via embarassing pop drivel to eventual oblivion - all because the organisers caved in quickly to the "anything goes" format. Had they stuck to their guns I believe that the performers would have adapted to the genre and we would have had a unique (locally) and interesting session going.
Maybe it sounds more acceptable if you think of it as being "selective" rather than "exclusive". Anyway - why should we folkies believe we have a right to join any and every session?