Converting all text to outlines was a standard practice that was used in the industry about 10 - 20 years ago, if not longer, before PDFs were standard workflow.
This was when artwork files were being supplied, and to stop the sending of fonts (which is frowned upon) and to ensure the text didn't move, the text was outlined and supplied that way.
It really has no place in a modern workflow. But if you went from an industry role to a teaching role, you may be out of the loop on common practices and PDF workflows.
Yes a teacher must know what they teach, but they must also know why they are teaching it.
If the lessons happened in a cross-over period of the two workflows, which I think lasted about 5 years before people switched entirely.
It's probably still common practice in a lot of countries, with older technologies that don't work well with PDFs, and relying on some sort of PS RIP, or using EPS-F files etc.