People may not know it but at some point in the nineties you'd enter a bookstore and 95%+ of all the books and magazines were typeset using QuarkXPress.

Then Adobe's InDesign showed up in 1999 and things began to change.

FWIW I both wrote and typeset books myself (for a traditional publisher): I did most of them using QuarkXPress but I managed to sneak one I made with LaTeX (it was a hard sell to the publisher / printing press guys who were only ever using QuarkXPress). Also I was forced to heavily modify LaTeX templates to match exactly the one the publisher was using with QuarkXPress.

So yup when I read "Quarkdown is a modern Markdown-based typetting system" the first thing I think about is QuarkXPress: great memories of MacOS (8? then 9?, pre OS X for sure) and my Sony Trinitron monitor.