Self-guided learning is amazing but a lot of people struggle with the discipline involved. Often when you set out to study a topic you’re interested in, you find that it has prerequisites in other areas (such as calculus) that you may not be strong at or even actively avoid studying. For many people this can put an end to their self-guided study.

Attending a formal educational institution, on the other hand, has proven very effective at getting people to knuckle down and study calculus (or whatever their “blocker” discipline is) so that they can move on to studying what they’re really interested in.

Sure. I don't mean to downplay the value of educational institutions. I just want to stress that they aren't the only method of learning. Everyone needs some mix of self-guided and instructor-lead learning to succeed.