AsciiDoc is amazing. Take another look at the architecture diagram. AsciiDoc is listed under the Proposed Text Edit: https://i.imgur.com/8IMpAkN.png
Pandoc can convert between Markdown and AsciiDoc, so it really isn't an either-or decision. For much of the blog you can tell pandoc to use AsciiDoc as the source document instead of Markdown. The conversion to ConTeXt will (should?) generate the same output.
One feature of AsciiDoc that's quite appealing is cross-references. The main reason I gravitated towards Markdown was because of its simple and terse syntax.
At that point it's a matter of updating a few build scripts to pass AsciiDoc files to pandoc instead of Markdown. I wouldn't say starting with AsciiDoc would have been better or worse, just different. Starting with Microsoft Word would have been worse.
Pandoc can convert between Markdown and AsciiDoc, so it really isn't an either-or decision. For much of the blog you can tell pandoc to use AsciiDoc as the source document instead of Markdown. The conversion to ConTeXt will (should?) generate the same output.
One feature of AsciiDoc that's quite appealing is cross-references. The main reason I gravitated towards Markdown was because of its simple and terse syntax.