In the case of a dentist, you can not. (and more areas)
For Web Tech, you can learn a lot.
But parallel you must learn Greek or Russian or Arabic and more. And to write by hand, in order to make the brain active. And more to walk or go to Gym or have an animal or a farm in order to make to the body strong.
Because online courses have an opportunity cost, make humans lazy.
Better distance learning.