Perhaps UK Folk Clubs have become too concerned with bums on seats, and are happy to allow any kind of Acoustic Music, the positive of this is that it is a place for home made music, rather than passive music consumerism, the negative of this could be that you end up pleasing no one.
There are performers who want to just go to music sessions or singers who want to just sing blues, or singers who want to sing for example Scottish Traditional Bothy ballads, or singers who want to sing their own material.
Then there are some clubs where singers nights are more popular than guest nights, this might possibly indicate that there are some singers who do not want to listen to others, but just want to do their own thing, and a few of them are not aware of how mediocre they are.