It seems to me that it's really about reducing the options to the ones that enable you to do what you want to do. I don't really care whether anyone uses a thumb or not. I don't usually do it, because I've found other and, for my way of playing, better ways--even the Gary Davis stuff often can be often be done in another way.

Incidentally, a thousand "thank yous" to Don for posting the Django clip--I love the few   unaccompanied measures that he played   more than anything of his I've ever heard, and
I'd never quite understood how he did what he did with only two fingers. Now I've seen it, and it all seems so simple!