Chet W,
I agree with your main point that the ownership of a blues song is a contradiction in terms. It's like who got the tiredest at work today, IT AINT THE POINT!
In my limited studies I've learned that the old Delta masters wanted to give away thier music so it could live on. If it were otherwise, the history of Delta blues being developed on plantations where would be artists came and went could not have happened. The guys that knew how to play and sing would never have been willing to teach others. I've read that many of them believed that if they gave their music away, they would become immortal.
We can't own it, we can only hope to do it some justice.
That's my 2 bits.
Gene (not quite Delta enough yet) E