It benefits USADA because It makes them look good.How does it benefit USADA, aside from allowing them to do their job better?
It benefits the UFC because it is imperative that they market a clean sport, especially in the mainstream.
It benefits the clean fighters, because they don't have to spend their whole training camp working their ass off only to run into a TRT Vitor-esque superhuman. We talk all the time about how some guys completely lost it after USADA. That goes to show what they've done to maintain something that is as close to an even playing field as possible.
I agree with your points but you know anytime USADA calls about positive tests the UFC aren't jumping for joy. They're dreading the fallout since cancelling fights directly affects their bottom line.