If I would have had to learn it immediately I most likely would’ve felt disinterested and overwhelmed and given up since I didn’t know yet why I needed to learn it.
Build an application, then as you need to learn more to get things done you naturally pick up a deeper knowledge of the tech you're using.
Of course this is different for everyone.
I wonder whether the fundamental structure of curricula could be changed to take advantage of this fact, because I think it's true for a lot of people.
Additionally, code is more collaborative than that, and it shows in a lot of engineering departments when people aren't trained on how to look at the shelf for existing parts before building something new.