I always thought the whole point of a 'Session' is for it to be Inclusive

I don't think so and for regular events I tend to aim for more specialised (Irish instrumental), don't enjoy the worst you can get from off beat thumpers, shakers, prefer that 1/2 the night is not taken up by singing, etc.

I think of them as places for people shared interests and tastes to get together and with each having it's own ways.

It could well be that a festival session might be better by or need to cater for everything but I don't see that as the way all sessions should be.