Twaddle. There is no such thing as pure BDSM. There may be an original definition that brought the acronym together, but it is and always was intended to be a very broad pigeonhole, and the actual acts that go into that pigeonhole are almost without number. And not every one of us has at the core of our BDSM a master/slave dynamic (and certainly not a master says slave does dynamic). There isn't always a clear distinction between top and bottom, as anyone who's spent much time around 'submissive' men, a very large proportion of whom are topping from the bottom.
I love to wrestle my subs- and I love them to try to wrestle back. Having done a lot of MMA in my lifetime it's a lot of fun, especially when pinned and breathless they have no choice but to concede defeat. I find it far more an exhilaration than the sub doing as I say.
You missed my point entirely on Randy Couture. In your first post you said the loser doesn't give up but is pinned in wrestling. I maintain that Randy, a wrestler by training, uses his wrestling skills not to pin but to submit his opponents (when he's not ground and pounding on their faces). And you personally may not see MMA as mixed martial arts, but nontheless it's there. It was dominated by Brazilian jui jitsu in its past, but there have been many karateka, and lethal kickers like Mirko in the ranks of UFC. The only reason it's lost its way as a sport is because the competitors have had to evolve, take on each other's styles so there is a lot less distinction between the fighters' abilities these days. However, to say it's now just boxing and wrestling is not only a major simplification, it contradicts your own point that wrestling is solely about pinning.
Mike