There is far more value in skilled individual attention at the doing exercises stage - helping where people are stuck, figuring out which parts need revision - than at the lecture stage. Think about how college seminars work - you do the reading on your own, the learning happens when you're digging into it in a group setting.

Hey now we’re talking!

But seriously, teaching in public schools these days relies so much on technology, youtube, that it makes no sense to have teacher’s as paid professionals, just get subscriptions to technology services for the kids and teach them how to work them. I think we still need places to socialize kids, but that’s a different job. Anyway, yes, too many teachers are simply there to enforce unnecessary social hierarchies and rigid modes of thinking, there is no need for most of them.