@glyph @0xabad1dea a former employer of mine used (probably still uses to this day) telnet to talk to a domain-specific piece of software that was at the heart of their business, and which once upon a time was connected directly to glass teletypes.

Tweaking it usually caused more problems for the business than leaving it be (and had an eye-popping hourly billing rate), and a full upgrade to a "modern" solution would have been an appreciable capital outlay and risk to business continuity for very little feature gain aside from "the UI is now 100x worse because everything's squeezed through the browser"

(sure, we wrapped it in an SSH connection, but it was still telnet under the hood)