Nearly 40 years for me. Wow! I’d note that MacOS input fields also have basic Emacs bindings for cursor movement, not just shells and browsers. Works in MacOS Mail, Evernote, etc.
It annoys me so much to have learned that GTK text fields used to have an Emacs editing mode, which they've hidden behind an unaccessible configuration option, and now it's hopelessly broken in modern GTK version.
Yes, emacs keystrokes became kind of cli lingua franca, which apparently many do not know. I don't remember my self ever read about those supported explicitly anywhere, but accidentally I found out long time ago and then whenever I try new systems, programs and whatever I try which keystrokes do work. Quite often at least some work.
Wow, so you used the earliest public versions. Ever written a retrospective of what 40 years of Emacs has been like?