Buy why would you go through that trouble unless you don’t know concrete and only know framing? I see no benefit. It’s not cheaper, nor quicker, nor easier. I suppose if you have physical issues lifting heavy durock and mortar bags, you might prefer working with lighter wood, or possibly you know a way to cheap out on it, but to me it’s not sensible. What I believe is the case, is that a framer wants the opportunity to flaunt their skills, having only a hammer and seeing all problems as nails.