Situation awareness, de-escalation and threat assessment are all valid skill sets to have. I agree it's not an either or scenario with self-defense and MMA/sport, you can do both. A lot of the disagreements with these discussions stems from thinking that SD unarmed fighting skills are completely different than MMA/MA/sport unarmed fighting skills.
It could be for some. However, the points raised about the viability of MMA/sport training used in a physical altercation are valid. We can create scenarios which would make any type of training ineffective. In sparring(rolling, randori, striking) we and our sparring partners transition through various positions throughout the round. Striking: range(close, medium, long), bias, angle, inside, outside, etc. Grappling: full mount, side-control, back, north/south and a plethora of grip and guard variations. We train both how to attack and defend from these positions, all of which are positions you can find yourself in during an altercation, your starting position(s) means very little.