MacLeech They mostly died out in the early 80s
Actually, some travel “experts” still recommended having one into the 90s. The justification was that, if you were travelling on business, you could still connect using your laptop, and this, even when your hotel tried to restrict what you could plug into the jack (or there was no standard jack). That, of course, didn’t help you if they had additional charges for any use of the in-suite telephone, or an oddball handset that wouldn’t fit.