[kip_]

Some of us graybeards use to use teletypes to talk to our computers. In one of the earlier races between differing I/O, the printer couldn't print as fast as the teletype was receiving data, so the teletype would send XOFF (Ctrl-S) to tell the remote end "Stop sending data and let me catch up" and would then send XON (Ctrl-Q) to say "I'm caught up, go back to sending data.

Many of us carried that to our VT100 terminals and used it when lines of code or output would flood the screen faster than we could read.

Eventually paginators like 'more' and 'less' were invented and flow control via the keyboard codes for XON/XOFF fell out of favor, but some of us have very strong muscle memory. :)

[mdaniel]

A fine answer, but my life experience is that it's not just "muscle memory," I am showing that xon and xoff still work inside both Terminal.app and iTerm2 (echo $TERM shows "xterm-256color") so maybe there's some legacy stuff configured in them or something, but I'm just saying that I struggle to think of who the audience is that would be running micro but not via a virtual terminal library that implements flow control