User blog comment:ElizabethVictoria00Catasthrophe/Izuku is not really quirkless/@comment-35434208-20180422023203

His ability to control his quirk had to be manually learned from Gran Torino, All Might, and through his (fortunately very capable) intellect.

This is reasonable since even simple physical concepts such as walking (comparing since quirks are technically physical abilities) have to be helped along by your own understanding and like, your parents.

For example, if you are deaf, then you have to learn to speak (in speech therapy) since you don't learn in from society and the sounds of people (which was the case of everyone else since their quirks manifested early and they got used to it)