Where have I ever stated Marth is "stupid good"? I stated that he autorapes you in Melee if you don't wavedash out of shield. In general his gameplan has atrocious design and he's always been overloaded. So thus, he's a character that needed to be nerfed.
LOL, grabs don't lead to extremely long combo followups? Are you for real? Are we talking the game games? Grabs in Melee not only are one of the quickest ways to rack up REALLY HUGE DAMAGE from combos and chaingrabs, they lead to KOs. Grabs in 64 don't combo often but they hit like Smash Attacks. Only in Brawl a lot of the cast got shafted and can't guarantee really huge damage from throws, with some exceptions.
You're also missing the bigger point. Grab teching is necessary to prevent snowballing in ALL fighting games. It kinda doesn't matter in SF2 where you basically die in 2 combos anyway, and similarly in 64 you die in like 3 attacks. So who cares about grab teching in games where a touch kills you? But when you have to actually work for the KO, then the positional advantage you can create from a grab is OBSCENE if there is no reliable grab teching. Imagine SF4 if there was no grab teching. Right, and we want Cammy, Yun, C Viper, and Akuma to be more broken. It's also why Grappler characters tend to get shafted really hard in most respectable fighting games. Untechable throws are unfair to defend against, so thus, grapplers USUALLY have to be bad at getting in safely.
So what does no grab teching to in Smash? As I said, nobody cares about 64, given you die in 3 attacks anyway. In Melee, Fox, Falco, Sheik, and Marth are the only characters that get grabs in this game competitively, and Jigglypuff is also competitive because she can't be grabbed period. In Brawl as I recall, Metaknight is virtually UNCONTESTED by anyone except Olimar basically. I mean seriously, what do you do when Metaknight wants to grab you aside from HOPE he doesn't read your dodge given he can punish it SAFELY and for good damage?