Good point, but I think it's a little more complex than that.
To my knowledge (and what I meant by "old school"), it was common to type a "--" dash on typewriters[0] because most of them lacked en- and em-dashes, which are obviously not digital documentation devices.
But yes, typesetters of old (old, old school!) had myriad glyph blocks available to them for pressing!
The old school of writing it in digital documents. Typesetting predates and is not limited to digital documents.