"Performance standards are measured at the box office."
Not with folk song they're not Dick; folk music hasn't made the box office - not in the UK anyway, and the way some people ponce and fart around the music, it never will.
Singing to the best of your ability is, as far as I'm concerned, a matter of respect:
1. For the singers who have made, adapted, carried and passed on the songs so they didn't die out.
2. For the audience who have dragged themselves out from in front of a warm fire to come and listen to you.
3. For your fellow performers who have to pick the evening off the floor when you have mumbled your way tunelessly through a crib-sheet assisted song.
And as much as anything:
4. For yourself - can anybody possibly enjoy embarrassing themselves in public and sending home an audience home embarrassed on their behalf?

I believe that it lies well within the ability of most people to become, at the very least, competent singers providing they are prepared to put in the time, thought and effort into it - the difficulty seems to lie in persuading people that the songs are worth that time, thought and effort.
Thirty years ago MacColl told us:
"Now you might say that working and training to develop your voice to sing Nine Maidens A-milking Did Go or Lord Randall is calculated to destroy your original joy in singing, at least that's the argument that's put to me from time to time, or has been put to me from time to time by singers who should know better.
The better you can do a thing the more you enjoy it. Anybody who's ever tried to sing and got up in front of an audience and made a bloody mess of it knows that you're not enjoying it when you're making a balls of it, but you are enjoying it when it's working, when all the things you want to happen are happening. And that can happen without training, sure it can, but it's hit or miss. If you're training it can happen more, that's the difference. It can't happen every time, not with anybody, although your training can stand you in good stead, it's something to fall back on, a technique, you know. It's something that will at least make sure that you're not absolutely diabolical
The objective, really for the singer is to create a situation where when he starts to sing he's no longer worried about technique, he's done all that, and he can give the whole of his or her attention to the song itself she can give her or he can give his whole attention to the sheer act of enjoying the song."
That statement is as valid now as it was when he first made it.
Jim Carroll