Could you elaborate on the etc etc.? I work at a company that has a handful of full time remote people. They're mostly senior engineers who had to move for personal reasons but were too valuable to part with. We have Slack, we have networked conference rooms, we have email. We fly them in a few times a quarter.

Those employees do a good job on their work, but they're still compartmentalized. They don't participate in company-funded culture/morale boosting activities. They can't really break a problem down at a whiteboard with a group of engineers who are in the office. They can't participate in much of the interviewing process that brings new people into the company. They can't get coffee with that random junior person in sales who has some great ideas about the product but is hesitant to schedule a formal meeting with a senior engineer who's surely busy with far more important things. You get the picture...

I believe that a "remote-first" organization can work with the right people, but how does a primarily on-site org accommodate remote workers?

By "etc etc" I mean all of the technology available for conferencing, messaging, screen sharing etc. Yes, it's a bit of a hassle but not a major effort by any stretch of imagination. Whiteboarding - I actually find that diagrams drawn in a screen sharing meeting using any of the bazillion options available (giphy, visio, ms paint even) are way easier to comprehend than a picture of a whiteboard drawing.

Juinor ppl getting face time with architects/engineers - this is more of a company culture thing I think.