The vast majority of students never ask, “what if…” The vast majority just want to know the mechanics of doing the problems well enough to pass the test. At the time a student is taking Calculus 1 they don’t ask questions about why it works. They just want to know, for instance, the rules of differentiation. Later in life, when they have intellectually matured, videos like 3Blue1Brown are interesting and fascinating. The vast majority of students would not learn well from 3Blue1Brown type videos.