I just assume that he meant something like "text-chatted over Slack" when he wrote that. It is a perennial surprise to me that many developers will send an electronic message of some sort even to people that they literally sit next to.
I do that. The point isn't to avoid speaking, it's to avoid interrupting them.
This. I send chat messages to the engineers right next to me except when something's really urgent. It's bad to interrupt another engineer's flow unnecessarily.
Plus, it also avoids interrupting all the others in the same office.
I do this when I have a team that's partially remote. If any part of the team is remote, the whole team is remote, so you have conversations electronically for the benefit of the rest of the team, so they don't miss out.