I see exactly what you're saying and I agree: the kind of understanding your exposition gives is different than the kind of upskilling Math Academy can promise. My only thing here is (a) there's value in both approaches and (b) everything I've read about self-teaching math is that you can't get fluency without grinding problem sets.

I buy that you need both (and: I supplement MA with ChatGPT, which is pretty great at Socratically working through concepts), but also I cringe whenever people say "oh, you want to understand eigenvectors, just watch the 3blue1brown videos", because, those videos are great, and watching them in isolation gets you approximately 0% closer to being able to do (or appreciate) a PCA.

I think a set of videos like Strang's 18.06 and Math Academy (but for arbitrary subjects, like Calc II or undergrad Stat) would be a pretty killer combination. Are a killer combination, is what I mean to say. But I've only been at it a few months!