It would be nice for man pages to support Markdown format natively: easy formatting, links, tables, tooling, number of ready to use pages shipped with projects.
Pandoc can convert MarkDown to Man pages so in that sense we’re halfway there. (But I agree that native support would be nice.)
scdoc is similar to markdown.
I do not understand HN's obsession with Markdown. It's fundamentally a poorly specified, ambiguous, very limited format. And no, formalizing a single parsing algorithm for such a format doesn't solve the issues apart from different rendering in different viewer applications.
I just like it because it's a rough standard. Not the one I'd choose and, as you point out, ambiguous. But I can expect support in all kinds of random places.