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!

--

[0] - https://en.wikipedia.org/wiki/Typewriter#Typewriter_conventi...

On a typewriter you can write symbols overlapping, so if you write '--' it becomes '–'.