No, I took Heather Wood as an example of a singer who might have been excluded by those who insist on "standards". Her singing is a bit wobbly. Or at least some recordings are. But without her the Young Tradition (my absolute touchstone for forceful English harmony) would not have been what it was and the tradition that now includes their work (some of it was then contemporary) would be impoverished. I think she is wonderful. (I believe she now does a lot of filk, and one of her standards that no record company is brave enough to release is "The Wizard's Staff has a knob on the End", and another is "The Hedgehog can never be buggered at all").

None of these good things would have been if some policeman had said to her "You are not good enough, go away".   

Equally Peter Bellamy's low notes were almost wholly random, but somehow he found the key again on the way back up, every time. Should someone have said to him "Go away until you can sing in tune"?

Telling people they must go away does not create a thriving community.