The unfortunate reality is that a lot of success boils down to IQ (and some other metrics of mental acuity,) which is mostly hereditary or imprinted, so that's depressing for a lot of people in education who started off wide-eyed and optimistic.

Also, an efficient, nationwide online schooling system (CAVA in California as an example,) would be the end of something like 90% of the teachers in the country. Would that be a good thing or a bad thing? Who even knows...

Everything has trade-offs.