I'll give them credit for not just being another "markdown sucks, let's switch to RST" slop article. Even more so as they say they don't have a solution - because a solution would be like asking for 3/3 on "cheap, reliable, fast" or whatever your favorite version of "engineers are paid to make compromises" is.

Markdown is great at small-to-medium documents; LLMs seem to like it too possibly out of a combination of fairly logical design and lots of training examples.

Custom extensions like |||warning\nDisconnect from the internet befor trying this!\n||| get you a bit further and don't tie you into HTML.

The moment you need multiparagraph items including code blocks inside a numbered list that also has an unnumbered list child of which some of the items are images ... the person who set you that task probably doesn't understand good design, but regardless, I find you need something with an explicit tree structure, that is there are markers for both the start and end of each node such as <td> ... </td>. That necessarily makes the document harder to write, though at that complexity it'll probably be hard to read too.