My theory is that it’s an intuitive rate limiting scheme devised to cope with the corporate fire hose. There’s no limit on the amount of text coming into an office worker’s inbox in a unit of time. But if one focuses on verbal communication, there’s always going to be a single stream.

Personally, I don’t do this; instead I deal with the stress of the fire hose by grinding my teeth to stubs at night. And for the messages I don’t get to, instead of “let’s discuss”, the sender gets nothing at all.