Support in forums and such was needlessly short in using RTFM as an answer. People could have pasted a one paragraph pointer to the documentation intake path and that would have helped.
IRC being async if the client is run locally, modem delays made no difference (just as with QWKmail and forum posts). And for remote host IRC, I don’t remember what the IRC line length limit was but at 300bps you could get an entire message and the buffer scroll updates accompanying it in 1 second, which was well-sufficient enough to support peak volume with no relevant latency. And, I can still type a paragraph at clock seconds of input latency and remember where I’m at when backspacing. So, I would definitely not ascribe a desire for brevity as an outcome of modems.