That would make it vastly superior to the use of swords, staffs, and bows, neither of which allow you to chop off limbs or knock someone out.
I'd be wary of a grappliing system which allowed the player to be far more effective than a master swordsman is. If you allow grapplers to break limbs and choke people out, you need to allow swordsmen to chop off arms or bowmen to snipe people in the eye.
I agree with this. grappling needs to be balance to equivalent outcomes as regular melee options and magic/skill options.
At one of the martial arts camps I went to, we had a session with an expert at ground fighting. At its basics, I learned how to simply hold you down, so you can't get up, and how to maneuver myself while prone, so I was at reduced risk AND had the ability to trip and attack you from my back.
the hard styles of martial arts (kicking and punching) are easy to model the same as attacking with weapons.
The fuzzy stuff are the effects of the soft styles.
I can pin/immobilize/hold you.
I can injure you in a way that disables a limb (penalty to-hit?)
I can trip you (rules for that)
I can keep fighting while prone (being prone has no/little effect)
I can knock somebody out (sleep spell)
Just to name a few.
Historically, real fighters also know how to grapple. Boys are always wrestling. Men wrestle for sport. And all fights almost always end up on the ground. So medieval swordsman, probably knew more about grappling somebody than using a sword (an exageration, perhaps variable by level)