That's kind of like saying MIDI was never widely used because you only ever saw MIDI files used to play tinny soundcard music on someone's GeoShitties site back in the day. MIDI is much more a control protocol than a file format, and it was and is used as such throughout professional music production.

Similarly, PostScript was the control language for high-end printers back in the day, so it was used extensively as the final output format for print, even if it was rarely saved off as a .ps file.