This article is missing two important ways to learn HTML back in the day:
1) Read the source. Websites were simple. There was no JavaScript or CSS. Everything was right there in one file. If you saw a site you liked, just take a copy of the source and tweak it locally to understand how it works.
2) GUI tools. There was Frontpage and HoTMetaL and some others. These were actually pretty decent because there wasn't so much you could do with HTML. You could drag'n'drop your content, then clean up manually if you wanted.
Here's a live example of a 1995 website: http://www.os2ezine.com/v1n1/
Look at the source. It's easy to understand the basics of HTML just by comparing the source and output. Deeply nested divs and tables were not a thing yet.