I'm with weelittledrummer here. While I find the majority in the "folk" scene welcoming, the strings are definately pulled by individuals who have cornered the market, as it were, when it comes to handing out the favours.
What motivates their decisions is probably governed by supply and demand and/or the ability to get bums on seats. If I was being really paranoid I would say that certain artists are "pushed" because they are seen by these same manipulators as being the best bet in terms of either financial return or, possibly, the bearers of the torch ie safe hands to continue the tradition.
Whichever way you look at it many excellent artists are overlooked during this selection process and this causes resentment.

To me there's two categories in this world we call folk:

Fundamental Folk - in the hands of the ultra traditionalists

and New Folk - embraced by artists more interested in what's happening in the world today and tolerated by borderline traditionalists.

They both have their place and should be allowed to live side by side.