So I wasn't going to do this at first, since this is a lot. But I just had one of my players claim that the worst rules subsystem ever printed was 3e's grappling system. Here's my "sweet summer child" reply (and yes, it's technically cheating to put every subsystem you could use to incapacitate someone non-lethally without striking them with a weapon, but how could I post one without the others?):
Yes indeed. The 3rd ed grappling rules are actually quite GOOD, especially by comparison to every other version of unarmed combat rules D&D had up to that point.
The 3.x rules believably simulate the things you would expect grappling to do from consuming fiction and from a casual acquaintance with martial arts and sports involving grappling. They involve a roll to get a hold of someone and a separate step of actually fighting for control/pin or escape. They give the ability to put your hand over someone's mouth, to keep them from shouting an alarm or casting a spell. They give plausible rules for grappling someone and moving them where you want them. They give rules for it being easier for SOMEONE ELSE to stab either combatant while the grapplers are wrapped up and struggling with each other. They give rules for using a dagger or other short weapon IN the grapple.
The 3.x grappling rules are the ONLY set of D&D grappling rules to actually do all this. To let a grappling character do all the things we'd expect to be possible when grappling from real life and fiction.
Of course, the cost for all this verisimilitude is complexity. Unless you had a member of the crew who was really good at memorizing, every time a grapple was initiated you'd have to bust out the rulebook to review the steps and rules again. And, this being 3.x, an optimized character could "break" the system by stacking up huge bonuses to grapple. We had a Druid in one of our campaigns who specialized in grappling people, especially while wildshaped into an increasingly larger and larger series of bears (same guy previously had a Ranger/Drunken Master who also grappled regularly). Between big Strength bonuses and Size bonuses, he was able to wrap up and make helpless increasingly tougher foes. The DM could come up with counters of course, but it was a bit much at points.
4E simplified the hell out of it for playability, ease of use, and balance, but lost the ability to simulate most of the things we see grapplers do in fiction and life. And 5E added a little more back to it, but still much simplified and limited in scope.
By comparison, all the rules 1E had for them are relatively lame and not particularly evocative in effect if you get them to work, and absurdly complex, lengthy, and annoying to use. They make the 3E rules look like a marvel of concision and simplicity by comparison.