Now consider hits to the back of the head. If an MMA fighter exposes the back of his head to you, the quickest way to end it would be a palm strike to the base of the skull: lights out. But because that's illegal fighters will be a lot more likely to go for something like a rear naked choke, taking the fight to the ground and artificially inflating the value of grappling.
And that's just three of the many illegal moves.
not really. If you look at a good boxer during a fight, you'd not see any opening for a throat strike.
Boxing, being one of the most practically efficient techniques at the "upper floor", is perceived and frequently really is missing at the "ground floor" and this is where Muai Thai comes in - basically extending the boxing for hands with the boxing for legs, as out of the many footwork styles - taekwondo, karate, kung-fu - the Muai Thai's footwork is the most similar to the boxing ideology and style.
I think it's similar in physical combat, although some elements like the dropped elbows and kicking a downed opponent would definitely end a match faster, you have to drop them first.
Still, I agree with your point that UFC shows us the best mix of skills for that particular set of constraints, not necessarily for self defense in the outside world.
Also, in sports there is always the occasional surprise new technique that dominates for a while until others train to counter it. In the early days of MMA grappling alone could win, as long as you had a finishing move (which is why early on some of the huge greco roman wrestlers could dominate a match and still lose).
Pulling off eye gouging and throat strikes are low probability and expose a fighter. Bas Rutten has a bit on these techniques, their effectiveness, and how doing either leaves an opening.
A throat strike is no lower probability or more exposing than pulling off a punch to the face. It's just a couple inches away...
To emphasize trhway's dose of reality, here's Bernard Hopkins explaining proper technique with the chin to avoid getting knocked out.[0] Throat punching is hard to pull off because proper defense doesn't allow for it.