I find quite a number of online courses that work well for those who are interested in the subject.
The classic examples would be to watch you-tube lessons from Richard Feynman or Milton Friedman.
These are great, but that’s not a college course.
Testing and evaluation, networking, in person communications, tutoring, help by the instructor, labs are all not possible or reduced severely in their effectiveness with on-line.
Part of a college class are the debates, the off record communications with an instructor that dispenses personal experience which runs contrary to what’s in a textbook... With most of these online classes the instructors are basically handed a complete course and told what to do say with little to no input by them. They are a highly qualified presenter and no more. Also, the lack of physical interaction face to face is a concern since people need that.
Technology can be great. But trying to use it beyond its actual effective limit doesn’t work well.