You're missing that part where soft contribution is dropped. It's doing less work because the person aren't sharing skills and knowledge with the wider organization. That is valued work.
Is it really, though?
Chatting over Slack can help everyone involved as it cuts down on meetings or even the need to focus synchronously on someone else's issue, and you can create group meetings with a couple of clicks. It's also trivial to setup an internal wiki.
It sounds like you're up selling in-person meetings while completely ignoring how everyone has been working for two years now.
Frankly, relying on knowledge sharing being a deliberate practice seems like a good tradeoff if what is lost is the random osmosis facilitated by overhearing highly distracting conversations, which is even less reliable than rumor.