the things which are added to plaintext to make HTML make parsing simpler for the computer and more difficult for the human
This is the crux of where we disagree. <title> exists to be human readable. A machine would be happier with a binary identifier.
A human does not need additional training to utilize every character in a Markdown file
Uhh ask any non-tech person to write a markdown file. This simply is not true.
A header 2 tag (h2) in HTML requires no more training than a header 2 tag (##) in Markdown. They both exist to make it easier for a human to dictate to a machine what should happen.