Markdown is the native formatting of large language models. As such, support for it will be everywhere in the coming years.
I suspect LLMs, not users, have been the requesting this feature at Apple.
That's actually a nice perk since I have LLMs summarize or re-word my research findings quite often. I'm a disorganized person, so they've been a big help with me organizing my work.
I also like that Markdown is being added since it's what I typically use for documentation (github, etc). The default formatting in notes currently leaves something to be desired...
Shortcuts has Rich Text -> Markdown and Markdown -> Rich Text actions.
I made a couple quick shortcuts to go both ways, with the clipboard as both the input and output. I put a widget for this on my desktop and it makes it pretty easy. Not as easy as native support, but not bad.