Also complicated, but speaking from my own experience, I think we need to distinguish "grappling" in the sense of joint and/or pressure point manipulation, from "throwing" techniques in the sense of smashing your opponent into the ground, and from "wrestling" in the sense of both parties on the ground attempting to render one another prone.
I just meant in the sense of removing someone's ability to swing something at you/gaining control of the limb holding the weapon. I think a couple people have asked "what's the best martial art against someone with a weapon when you're unarmed." My answer is that if you're forced into that situation where you absolutely have to fight and there's nothing else you can make use of, the best answer is to disable the other person's advantage.
Joint manipulation is a popular thing, but...in my opinion, it is highly over rated. An awful lot of joint manipulation techniques can be completely avoided just by rotating an arm or shifting your weight by a tiny amount.
Since wrestling is all about this, I can tell you that it's more skill than any random set of factors like wrist size. If any inexperienced person tries to grab your wrist, you really can just twist right out of it super easily. It's not going to work as easily on someone who has practice holding on to someone trying to break that grip. Strength is a large factor, but so is technique. I wouldn't count in it in a real fight, but I have gained control of people much larger and stronger than me.
There are also a significant number of people on whom pressure point techniques just flat out don't work. They either don't have the nerves they're supposed to, or they've grown enough muscle over them that it's impractical to get to them.
This reminds me of a hilarious wrestling match I once had. I have unusually flexible arms. I can make an X behind my back to just past the elbow before it really starts to hurt, and could touch my shoulders together in front of me when I was younger. When my turn came to start the round on bottom, my opponent tried to force me down onto my chest by wrenching my arms behind me as hard as he could. I laughed pretty hard when watching a video of the match later, because he did this for like 10-15 seconds and twisted my arm very far back without any reaction from me. When he finally gave up on that approach, he actually threw his hands up in the air in a confused/exasperated gesture, which is when I was finally able to escape.
But anyway, I have almost no experience in real fights and zero in martial arts, so I acknowledge your expert opinion over mine on anything outside of pure wrestling.