You should think of Khan Academy as an average high school lecture course, aimed at an audience of typical students, and with an approach and exercises closely

You should think of Khan Academy as an average high school lecture course, aimed at an audience of typical students, and with an approach and exercises closely aligned to the standard (frankly, quite uninspiring) USA school curriculum. It isn’t the best possible quality, but it does have 2 big advantages: (1) it is self-paced and available to anyone anytime, and (2) it is consistently okay, setting a quality floor. Human teachers are more variable in quality. 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.