Why wouldn't someone just do this with their brain?
19 karma · joined March 23, 2017
Email's maturity by the time that businesses all came online pretty much guaranteed it as the standard for business communication, and personal use was just a small step from there.
Expecting 20s RTT for email is a modern phenomenon, when you could expect replies on the timescale of days before.
The closest attempt to a standard for IM is probably XMPP, which providers have pretty much all ignored in favour of lock-in to their respective platforms.