I'd like to weigh in on this with a quick parallel to MMA for a second. Some fighters don't punch as hard as others, that's just the way it is. Some don't take punches as hard as others. If, for example, Chael Sonnen hit as hard as a guy like Chris Weidman, he could have conceivably been champion instead of losing a fight wherein he hit the champ 300 (more or less) times over the course of 22 minutes and change before getting submitted.
In an instance like this, a guy like Chael Sonnen in my opinion has maxed out his potential in terms of practice and dedicatio as a martial artist, given that he has spent his entire waking life as a wrestler and was an Olympic alternate. However, having put in countless hours, days, years of wrestling simply wasn't enough to make him better than the very best guy, who could take all of his pressure and eat his punches without being finished.
I think something similar would apply to fighting games, if circumstances were similar enough to allow. Could I (just for example) practice MKX for 25 years training hours daily and memorize data and improve immensely? (assuming in this hypothetical world that MKX is still alive by then)? Sure. But if Sonic keeps playing and practicing (even if not as frequently) as well in that time frame, will it be enough? I don't know. Some people, I believe, are handed gifts at birth which separate them from the pack when the lights shine the brightest and the stakes are the highest. Hopefully this made enough sense to be a worthwhile comparison.
EDIT: Sorry youph if you've gotten this response like 6 times already, I didn't care to read the rest of the thread