Concert venues need to put on people who can perform.

However folk club singarounds are a different situation.

I think some distinctions need to be made. I go to a folk club (with a stage) & a singaround in a pub backroom. At the folk club you pay on the door, there's a raffle halfway through and 30-40 people usually turn up, of whom about 20 do a song - mostly originals or cover versions, some blues, some C&W and a smidgen of trad. The singaround has no entry charge and no raffle; 10-20 people turn up, almost all of whom do a song or two.

I go to the folk club to meet people, have a laugh and relax, and to get a bit of practice singing to an audience. It's precisely the kind of "come one, come all" environment autoharpbob described: get up and have a go, and you'll get a round of applause. All good fun, but the singaround is where I go to hear (and sing!) traditional songs. The standard of performance at the singaround is much higher - we're among friends, but the friends we're among are people who love folk songs and want to hear them done well. (And "well" doesn't necessarily mean "to a high technical standard" - passion and love of the material count for much more than remembering every word and nailing every note.)

It comes down to the difference between

a) Paying a tenner, sitting in rows and hearing it done properly
b) Paying a pound or two and getting up and having a bash in front of a sympathetic audience
c) Paying nothing and singing your heart out in the refrain of a song you'd never heard before that evening

They're all fun to do - the question is which of them is going to keep traditional music alive (or on life-support). To me there's no question that c) is a better model than b).