As someone who has a reading disability (but went to an Ivy League university), I can assure you from personal experience that I got 85% of my knowledge from lectures and 15% from textbooks, though I tried sincerely hard to do all the reading assignments.

Plus, there is the cone of learning. We retain a lot more of what we hear than what we read silently.

The Cone of Learning is the key to the answer. We retain a lot more of what we hear than what we read silently.

It's analogous (though not as extreme) as arguing that music students who can read notes don't need to listen to music, they can just read the sheet music. You're not stimulating as wide a range of nerve receptors.

(less relevantly, as someone who has a reading disability (but went to an Ivy League university), I can assure you from personal experience that I got 85% of my knowledge from lectures and 15% from textbooks, though I tried sincerely hard to do all the reading assignments.)