Comment by astrobe_

Yes, it's not markup but typesetting [1]. Well before 2013 people used to use stars, _underscores_ or /slashes/ in Usenet forums or mailing lists to mimic typesetting, which lead to Markdown.

The name still maintains the confusion as it tries to be an alternative to markup systems such as HTML which had the purpose to introduce semantic clues for computers.

We all know how it went; the semantic part was entirely thrown away and markup was thoroughly abused for layout (HTML tables before CSS - CSS which also has little to do with "style" and more to do with typesetting and layout), as no browser today can just show a table of contents based on the HTML title tags.

[1] https://en.wikipedia.org/wiki/Typesetting