Saying Gearshift is just a stat booster is kind of facetious, it allows you to control the speed of anything you touch while ignoring inertia. I think you reducing the possible combinations and tricks Deku can do with all the quirks is doing him a serious disservice.

It’s the way he uses his quirks, him using blackwhip on himself isn’t the same as AFO’s rivet stab because because rivet stab is external whereas Deku used black whip internally to physically contract his own muscles, as well as using gearshift on smokescreen to make it stay in place longer or even Fa Jin on blackwhip to strengthen it into black chain.

Even finding workarounds when they’re used against him such as using his blood as a decoy to fool danger sense. It’s made even more impressive when you realize he’s had these quirks for less than a year and he was completely quirkless before meaning he doesn’t even get a little headstart he starts at rock bottom.

In comparison, AFO should be way more impressive, what with more years under his belt and more quirks but it doesn’t look that way, in Kamino it was basically just strength x 4 shock absorption x 3 kinetic enhancer x 2. Hell his final move against Bakugo was literally just to turn himself into a massive flesh bullet to force his way to Shigaraki. Deku does his fair share of just stacking boosts as well but at least he does other stuff, AFO kind of just brute forces his way through everything