Palhares doesn't get subbed in MMA because he's one of the rare BJJ based fighters and considered a legit submissions specialist, not some MMA fighter who worked on their sub game. If we're talking grappling, he largely doesn't get subbed because he's unusually strong, as in steroids to the nth degree strong, not simply strong. Hermes Franca, a small, stalky guy got subbed over 9 times, and he's supposed to be submission based. Gary Tonon, one of my favorite fighters was dismantled by Keenan's technique and IMO, long limbs which make it easy to quasi-gift rap opponents....
Like I said, Galvao is the perfect example of short and stalky, and he was going off on height, talking about how much harder it is for someone short to control and sub someone tall, assuming their skill is reasonably close. Wallid tapped Royce because Wallid was an active competitor, taught by Carlson and stayed to learn jiu-jitsu in Brazil while Royce went to America at 19 and only learned mainly from Rorion at that point. Ralek, Ryron, Rener, all tall guys, all giving shorter guys with more competition experience and great skill, tremendous fits. Ralek's match with Tonon took way long simply because Ralek looked like an NBA player compared to him.
You can pull on a tall guy's arm all day, but if his elbow joint is closer to your chest instead of near your crotch because he's a beanstalk, it's going to be hard to get that armbar. A chock may be easier on a lanky person who is tall, but try getting through their frames, a tall guy can frame you so much more effectively.
Roger can be on the bottom and literally reach around the opponent's back to grab THE OPPOSITE LAT to pull himself up and around to take the back, he's done this so many times.
I think Galvao nailed it with his descriptions on Flograppling, obviously it's just my opinion, we can agree to disagree.