But RFC did not come from IETF. It preceded IETF by some years.
Steve Crocker led the development of a protocol called NCP (network control program/protocol) beginning around 1968 as the ARPANET was being built by Bolt Beranek and Newman. He and I and Jon Postel were at UCLA as graduate students working in Len Kleinrock's Network Measurement Lab. April 1, 1969, Steve wrote RFC #1 - he knew that we needed to document our design work but was very conscious of the fact that we were just graduate students, not the principal investigators on the ARPANET project. Early in the a.m. he was casting about for some way to describe these documents and came up with "Request for Comments" - a kind of humble way of saying "we're just rank amateurs, can you help us make this design any better".
Jon Postel became the editor of the series - a task he performed until his too-early death in 1998. The term stuck and was adopted later by the Internet Activities Board (which is now the Internet Architecture Board) and the Internet Engineering Task Force that was actually one of the dozen or so task forces that made up the IAB in its "activities board" incarnation (which came in 1983 by the way, as the Internet rolled out across the ARPA-sponsored academic landscape, and the US Military).