So the markup dialect that's widely used but suffers from a near-total lack of viewers will now finally be rendered as intended, at least on Windows?

Markdown presents a chicken-&-egg scenario that has dragged on for decades: tons of Markdown documents, but almost nothing with which to simply view (not edit) them as intended. Mystifying.

The point of markdown is that it is human-readable not only in "rendered" html form, but plain text too.

I think this explains the lack of viewers; they are simply not needed.

https://github.com/rabfulton/ViewMD

Markdown viewer for Linux

At this point I really think GitHub should formally publish their flavor as well as a default implementation. It's likely the single most widely used variant online at this point.

I know there are others and there are fine points. I would like to see a couple minor additions to support image placement (that aligns with Medium's editor) and finally a strike-through text notation. But that's about it.

PowerToys had a Markdown renderer for the Preview window added in version 0.16.0, which was released around late March 2020.

I used to write documentation in Markdown manually. About a year ago I started using a VSCode extension to tell me if there are minor errors in the documents, but nothing else.