Ironically, there's a good chance that the mockery of bloodletting was injected so strongly into popular media because it actually works. Both as a form of self-medicating that pharma can't profit from, and a means of removing things from your body that the government put there for a reason.

Also, it's worth noting that Gary Brecka - the guy who reversed Dana White's bad health - has some bloodletting in his process, though he doesn't call it that. He just draws some blood like a blood bank nurse would, but skips the banking part.