[ChancyChance]

I think the word you are looking for is "osmosis".

People learn faster when they have someone to teach them in a multi-modal environment. Videoconferencing is only a shadow of this, and everything is scheduled. There is zero chance for spontaneity with such a sterile structure.

I'm nearing the end of my career, but I certainly would not have learned as fast as I did without many, many mentors. Just reading the internet, especially when the technology is cutting edge and not even ON the internet, would have left me far behind. And if everyone falls behind, the company falls behind.

I think companies that mandate some amount of in-person time will have less risk of falling behind than those that are 100% remote.

I don't see how all of those junior 100% remote engineers will keep up. Maybe they are all just very very very smart.