for me the main point of a session is as many people joining in as can and having a good old time

And for me too. I've run my own session in my local pub for nearly 5 years now - through thick and thin, including a recent furore when the landlord and landlady decamped overnight, thus closing the pub for 10 days. I'm proud to say that everyone is welcome - regardless of skill or material - and the purpose of the evening is to make music, have fun, keep music live and join in good fellowship. I'm proud to say that people I've encouraged over time have summoned the strength to sing and play before people for the first time - and that's important.

As a host, these are my principles. As a musician, I have slightly different aspirations. One of the problems of "as many people joining in as can" - which I fully support - is that the opportunities to play something slightly more off the beaten track diminish. Or rather, not that they diminish but that you're out on your own, as I said in my first post. Which is a shame, IMO.