[SquareWheel]

That's fair. Semantic markup did exist pre-HTML5. I guess I should say that HTML5 emphasized it and drove adoption.

This article is from 2008, but I think it would be quite challenging to find something similar from 1999.

[combatentropy]

Semantic HTML was already fashionable in late 2004, when I was a graphic designer arguing against table tags. But my own exposure is a bad measure, just as is anyone else's. One of the most famous groups pushing for well-written HTML was WaSP, and it turns out that it was founded in 1998, https://en.wikipedia.org/wiki/Web_Standards_Project