All I meant is that you could have a hundred or two hundred people there and the atmosphere might seem a bit sterile - but you could have just a few people and it could be quite nice.

I've certainly been to concerts like that. Excellent music - but somehow the room wasn't charged with atmosphere.

The atmosphere is definitely one of the components of folksong. A bit like phlogiston that the old alchemists said that you needed to produce gold.

You can't quantify folkmusic. Its a qualitative thing, I believe.   Although some of it I suspect is down to the gravitas and experience that the performer brings to his task.