Some things can not be taught online. You can’t teach someone how to swim online. You should not try to teach someone brain surgery online. More generally, for subjects that are really difficult* one should have all of the teaching tools and environments available. This will include the internet but should not be limited to only the internet. Totally online instruction is better than nothing,** but not as good as the real thing.
* Quantum mechanics and relativity, for example.
** And may be used in real emergencies like the covid-19 pandemic.