Org mode is a coherent whole, and has capabilities far beyond what Markdown can accomplish (Markdown is inherently HTML-based, org-mode is not). Markdown's history is littered with folks trying to augment it in just the right way to bring these sorts of features, which has resulted in a diaspora of flavors, none particularly dominant+powerful (which is to say, no real org-mode competitor has emerged, even though one could have). I've used Markdown and Org-mode for 20 years concurrently, and trying to make Markdown work like org-mode has never been successful for me.

I wrote a bit about this back in 2021, in response to a query on Reddit "Why didn't org-mode just use Markdown?".

https://rpdillon.net/why-doesnt-emacs-org-mode-just-use-mark...