Going further back to Aldus Pagemaker. Plus, I come from a time of Quark and SyQuest drives to move data around. Things were different in the stone ages. PDFs were not a thing people used.

When I worked in print design, we’d typically send two things to the printer: a zip of the Quark or InDesign “collect for output,” and a PDF for reference.

Later, though, I seem to recall some printers accepting PDF/x-1a files – I don’t know if the industry has transitioned to that now, or if some still prefer a collect for output.