First of all no, school fails miserably at actually teaching anyone to learn effectively, so that's not why they do that. Second, they could just as effectively teach kids how to learn by teaching them things that are actually useful. I would've loved to have classes for note taking and studying, critical thinking, maintenance and repair... instead I've had to teach myself all of those things, meanwhile my school was too busy making me read about Victorian era dress styles to teach me any of that. Even math beyond algebra 1 is fairly niche and is probably better taught specifically to the people who need it. I'm in comp sci, I use that math all the time, but my friend getting his master's in plant breeding probably doesn't need to be intimately familiar with calculus.

It feels better to tell ourselves that all of the years wasted by school are actually for something but the reality is that school just does kind of a bad job at equipping people with the skills they need, and it needs to be improved dramatically.