Bendo does this all the time, most recently against Diaz. It lets him generate a lot of power for his GnP and keeps him safe from most submissions, yet the majority of MMA fighters seem content to just sit in guard and work weaker strikes or lower pecentage guard passes from there. I can recall Diego Sanchez standing up out of guard to attack as well, but other than that not many names spring to mind. From my limited experience, it seems to be the same in pure BJJ. I've been training for a few years now, and I often find that it's easier to pass guard from standing than on my knees. I'm reluctant to place too much stock in this when compared with MMA since I usually train with a gi so it might not cross over as well as you'd think, but then I watch a fight like Bendo-Diaz and it seems to be really effective, both in terms of passing the guard and for striking. I'd assume that it had to do with letting your opponent back to their feet, but Henderson seems to keep a good level of control while standing. Whenever they move to get back up he can usually grab the legs and move in to side control or half guard, which is obviously even better for him. So is there another downside to this that I'm missing, or has it just not caught on yet for some reason?