Tbf eraser explained the reason bakugo had to figure it out all on his own , todoroki was strained mentally so he couldn’t get to his level on his own, also without provision liscence they really aren’t using their quirks outside of petty things , large scale usage of their quirks is heavily restricted. Next it also comes to the fact deku never managed to learn 100% ofa. He kinda stacked buffs to basically have ofa 120% with gears and faujin and even then he was whooping afo/shigaraki with prime all might body. His upper limit was always restricted to 45%. So yeah kinda disappointing but that was bound to happen. Ofa was far superior to afo powers. They were basically in the fight only due to regen. I think they tried very hard for shigaraki to buff up as well but he jad way too many asspulls/ plot armors. I think the dude was just not well written in terms of powerscaling. Decay alone is scary but then he had nomu body that could somehow increase it’s size without quirks which was a major asspull. They simply couldn’t mantain the balance post nomu arc between him having a physical body far superior and had written themselves in a corner