Redact:
Describing it as "a small mistake" reflects an error in your mental approach to the IC matchup. A sync'ed grab under appropriate conditions means:
--you failed to keep Nana separated from Popo
--having failed to do so, you then spaced horribly (given how poor the ICs grab range is) or used a tremendously laggy move at the wrong time, or something like that
--having been grabbed, assuming it was possible to do so you then didn't mash out
So that's a threefold error in your entire gameplay against ICs, and mistakes of that magnitude deserve to be punished pretty soundly.
So even if it IS a simple command having landed the conditions, who cares? If it was really hard but masterable, it would *still* be "the player versus his execution," a scenario that comes into play way more often in Melee than people like to believe.
Falcon gets a grab after a certain percent, he's guaranteed a KO on most characters. He just has to track DI and land his knee or whatever. Falcon versus his execution, because the opponent's DI really doesn't affect the outcome unless the Falcon assumes he knows where they will go and screws up. Does this violate any kind of competitive spirit of Melee? No, because if you get grabbed, you pay for it. If the other guy screws up you may get your second chance but it's really NOT that hard to d-throw knee. It's so powerful that there is typically no useful alternative, so it even removes strategic decision making from the Falcon player. Peach is at 80% or higher? Camp for d-throw knee. Marth is at 80%? Camp for d-throw knee.
The power isn't quite comparable, but many of the factors you complain about are present here, and you already said that the power of the technique isn't why wobbling should be banned anyhow, so we can safely say that's irrelevant in this comparison.
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Also, if "situational" isn't the problem either and it's "lack of control," why isn't the ICs handoff banned as well? It's an inescapable CG that can be zero to death in a pretty good chunk of grab circumstances, and there are a pretty hefty # of setups that can lead to a handoff. Your DI doesn't matter, mashing doesn't matter, it's just the IC player versus his own execution. Why is this legal, but wobbling is not?