The last two times I've talked about grapplers, they've been characters whose high damage, reach and throws have been compensated for with poor mobility. With the King of Fighters series, SNK decided to try a different tack.
They let grapplers move exactly the same way everyone else can. In 94 and 95 they could sidestep the same as anyone else. From 96 onwards when everyone gained the ability to run and hop at half the regular jump height, the grapplers weren't exempt. Sure Daimon may not run as fast as Kyo, but the fact remains that he can play the neutral game the same way any other character lacking a fireball can.
Command throws (any throw with a special input) normally aren't a thing you combo into unless the game has some funky rules permitting it. For example, you can combo into throws in Street Fighter 4 if the opponent's in the crumple state from Focus Attacks. In Guilty Gear you can throw someone who's in a stagger state (which led to XX Slayer's notorious infinite thanks to some other rules about how throws worked). In KOF, you can combo into a command throw just like any other special move. Grapplers don't have to be given wonky special tools, or even really pay attention to what they're inputting. If you're pressuring someone in KOF with normals and land a hit, you throw them. If you're pressuring and they keep blocking, you can still throw them. Grapplers get to play by the same rules everyone else does.
So from this, there's pretty much two reasons that grapplers wind up top tier in a KOF. Let's take a look at what they are.
1. Like, half the cast are grapplers. No really. SNK are incredibly liberal with who they give throw specials to. You get characters with rushpunches like Shen Woo wielding them. You get mid-range pokes + high damage characters like Benimaru with them. Are you a pure zoner like Athena whose game is mostly about fireballs? Hell yeah you get a throw. Are you a main character's rival with a rekka for pressure, an uppercut for defense, a fireball for space control and some of the craziest crossup air normals? Damn straight you get a command throw as well. What's that? You don't have a throw? Check your movelist - one of your supers might be a throw! When characters like Daimon wind up weaker than the rest in a KOF, it's because there's other grapplers who just happen to have even more tools than him.
2. SNK often gave characters really dumb specific things that push the pure grappler up there.
KOF games had barely any testing until Console 13, so all sorts of weird bugs and ideas popped up. As a non-grappler example, there's a stage in KOF95 where characters jump into a boxing ringe as the ROUND 1. READY... GO. starts. Characters have different jump heights and speeds, so they get to start playing at different times. This means that on this stage, Iori can perform an infinite on Chin at the start of the round with Chin having no way to escape yet since he hasn't actually got control of himself.
Sometimes grapplers got dumb things like that. In 98, Daimon's standing light kick (st.B or 5B) did about 8% of your life. In MAX mode (which cost a bar), it did 12%. That's about as much damage as a light piledriver from Zangief in Ultra Street Fighter 4. This from a normal that reached really far and hit low. He could force you to respect this damn kick then run up and throw you. After he threw you, he would whiff his throw a bunch of times to gain enough meter to put him back in MAX mode or do a blowback should you manage to make him block.
In 98, Ralf's crouching heavy punch (cr.C or 2C) only had 2 frames of startup. That's the same speed as Chun-Li's super in SF3: Third Strike.
In 2000 there were assists. Joe's assist picked opponents up off the ground and forced them back into a standing position. This meant that if Clark had spare assists stocked and landed a throw, he'd take off a good 80% of your life before he'd even tacked on a super at the end.
In Arcade KOF13, Raiden didn't even care about his throw. He had a dropkick performed by holding a kick button then releasing it after enough time had passed. At its max power (holding for 16) seconds, it knocked away half your guard bar on block, was completely invincible, unpunishable, and comboed from everything. It dealt about 45% of your life. He could charge two of these. You had 16 seconds to take down Raiden before he just flat-out killed you.
Clark is scary in KOF13 because he can option select his jumping C with his airthrow, leading to safe jumps on knocked down opponents that also prevent wakeup uppercuts and jumping away. That guy can stay on top of you in ways 98 Ralf could only dream of.
Of course, plenty of throw-less characters wound up strong over the years. Nevertheless, part of the reason that Mr. Karate and Iori are considered two of the best characters in Console KOF13 is because their already impressive array of pressure, damage, high/low guessing games and setups are accompanied with the looming threat of their command grabs.
So what's the lesson? Perhaps it's that the lumbering giant with the spinning piledriver is an outdate way of thinking about who whould be allowed to throw people. I haven't even started talking about how literally the entire cast of the Vampire series has command grabs...