Markdown has two substantial benefits: Easy to store format that is easy to convert into HTML.
All native support would do is lot in a specific Markdown feature set, specific markdown styling, and specific Markdown syntax.
If you then tried to make a browser supported subset of Markdown that you then allowed to be customised, you'd wind up with so much goop that nobody would be happy.
Markdown has two substantial benefits: Easy to store format that is easy to convert into HTML.
All native support would do is lot in a specific Markdown feature set, specific markdown styling, and specific Markdown syntax.
If you then tried to make a browser supported subset of Markdown that you then allowed to be customised, you'd wind up with so much goop that nobody would be happy.
Also, this: https://xkcd.com/927/