Documentation is not a complete fix. So you have 1000 pages of documentation. Which page has the answer to your question? At work you ask your coworker with more experience "Can you tell me how X works?" and get an answer immediately. On remote you type in to chat "Can you tell me how X works?" you get an answer in 5 seconds, or 30 or 5 minutes, or 10 or 3hrs later, or never. Where as in the WFO example you were back to work immediately with little to no context switching, in the remote example you might have to just go work on something else (30-60 minute context switch) while you wait for an answer, then once you get it do another 30-60 minute context switch to get back into whatever it was you were doing.

Maybe LLMs will solve this. Have them read the code and then be able to ask them questions about how it works?

It's not just docs though. Maybe it's going over an idea. "I'm thinking of solving this issue by doing X, what do you think?" Same, WFO, immediate answer. WFH, answer in 5 secs to 5hrs+ or never.

People will complain that getting a question takes them out of the zone. That might be true but it's never been true for any co-worker I've ever personally worked with. Nor with myself. It's always been easy and pleasant to answer a coworker's question. A few times a year I'm working on something so complicated I need to be uninterrupted for a few hours but that's rare, for me at least.