One could argue that it's mostly about learning obedience, how to worship the clock, and how to tolerate doing things that are arbitrary and stupid. School isn't to make us good people. It's to make us good employees.
I went to lunch with some coworkers the other day. The restaurant we went to told us there would be about a 5 minute wait because some machine or other was just repaired. One of my coworkers had a little freak-out about how long it was taking and stormed out to go to another restaurant. (And this was a "fast food" restaurant we were already at.) I'm pretty sure he hadn't finished walking to the next restaurant by the time we got our food, but waiting an extra few minutes was too much for him.
The rest of us had a minimal amount of patience and it was no big deal. He wasn't a slave to some clock and he didn't have to obey anyone telling him to wait. But he also didn't get what he claimed he wanted (to be served faster).
That beeing said, mass teaching like we do it might not be the best thing. We have tools to facilitate teaching that for example does not require everyone to be at the same physical location. Those same tools could also be better utilized in work to enable remote work. Which would then mean one less life skill to teach at school.
I do agree, otherwise. Schooling has an orthogonal purpose to education at large, even though individual schooling systems might have higher educational value than others.