> I don’t want Notes to become a Markdown editor
> I’m just asking for it to handle a few more things.
How is what you're asking for not making Notes into a Markdown editor? Those are all features that come from Markdown, and the reason "most apps" already handle those, is because they're aiming to support Markdown to at least some extent.
I think the parent's suggesting that they should be "one way" shortcuts; i.e. "# Heading" auto-formatting as a heading is a shortcut, and it doesn't allow you to go back and modify the original markdown.