It's not just videos of someone going through the motions of solving problems. These are interactive explorations of mathematics.
I understand that it's step by step for the general audience, but KA applies this very slow, remedial structure to everything. The throughput was so bad I quit many series because of desperation.
Some MIT OCW recitation videos are examples of how to do this right. The lesson-giver has surgical precision and gets right to the point. Here's this problem/subject, and here's the relevant knowledge nugget. They'll mention what built up to this problem, which is amazing for discovering prerequisites - but never discuss those in depth. (I believe videos are not the most optimal way to learn in general, but in review and understanding they are very good.)
KA, on the other hand, goes into needless detail and redundance. (It's fine if you mention how demand graphs are relevant, but don't explain the basics of demand graphs again! I'm watching a more specific topic!).
That's how you end up with a long series of videos with sparse knowledge where, after six videos of ten minutes each, you have learned squat and the words "oh, let me use this pen color..." resonate in your head.
Before his controversies, Lewin's Course 8 classes/recitations were a gold standard in Physics learning. He combined intuition and rigour masterfully - along with some brilliant practical experiences.
The recurring theme in many courses (not only Lewin's, but Calculus, Economics, or even Strang's linear algebra) is the great care and preparation of the materials to get the point across. I think this, more often than not, is very successful.
As a society, we could definitely aspire to producing much better materials, but even though I myself would never use it, I’m glad that Khan Academy exists.