Markdown is trash. It almost always comes in a fork that is naturally incompatible with other forks & never has the features you need for blogging or technical writing (leading to abuse of the limited features, unsemantic markup output, and/or embedding HTML which is both ugly & also ruining portability to non-HTML targets). This leaves you locked into some specific tool’s forked implementation & never looks good in other contexts. Markdown was also never the only or best option for lightweight markup at any time.
Downvotes here showing it’s controversial, but I am willing to bet these folk have never given AsciiDoc, reStructuredText, & LaTeX a spin in comparison (for ‘real world’ documentation, etc. with multiple output targets) to actually know what they are talking about 😅
It’s always a series of extensions nonstandardized but said to all be under the same umbrella. It would be better if these things called a spade a spade & say Markdown-like or Markdown-inspired instead of giving a false sense of compatibility.