Yes, the author conflates two different use-cases.

Markdown is the answer for "how do we enable people that don't want to invest a lot of time into producing content that's somewhat better than plain text?".

It's not trying to solve the problem of "how do we enable people that are willing to invest time into learning to produce the best possible and most structured content possible?" and I doubt that there will be language that will serve both of those use-cases very well.

One downside here is that as more and more tools focus on the first use-case, people start using those tools by default when they actually fall into the second use-case. And there's often a pretty high barrier to switching once you've produced a lot of content, so a bunch of projects are using the wrong one long-term.