Finding a student/junior who is able to do well in your business environment at a distance does not imply that it is scalable across all workers businesses need to hire.

If you truly need an in-person job or employee, you can find one.

Not at all. Even if there was such a thing as "mandatory remote work", that does not preclude going to an office. Remote work allows working from anywhere.

The premise is that, absent of job obligation, there is little reason for the seniors to show up at the same place as the juniors. If such obligation is placed on them then you have an RTO mandate.

Might be possible, but most can't do it from what I've seen.

So if you go full wfh your pool of people who can mentor shrinks by a large factor (4x is my bet).

This is solved by having a structured mentorship program and guidelines, and really good onboarding.

Of course, this means businesses have to invest in this sort of thing, and of course, they don't, because they implicitly got it for free by having seniors covering for juniors for so many decades it obfuscated the problem

These are solved / solvable issues. Socialization at work can be facilitated in a myriad of ways, even remotely. Games are popular way of doing it, virtual happy hours, team building activities etc.

I wish I could emulate walking-over-there on zoom

There needs to be a normalization of "peeling off" the main chat room

at the end of the day after doing this I do feel more tired, but I get plenty of self-scheduled productive little discussions.

I still feel you're losing something without in-person (including social) interaction. I know for me personally, I would say I have much weaker connections to many people I've never met in person. That said, there are a bunch of other factors involved with building new connections as well that aren't purely about being virtual.