Apart from that, also back in the day people were still building pages using e.g. Dreamweaver, so we also put together a thing that could leverage a designer's HTML that rendered as a complete placeholder page. That "works as plain .HTML" became the template, used YAML as data, and Enlive (a Clojure lib) to turn the HTML with its placeholders into a template and then stuff YAML sidecar data into it to generate new HTML.

Not long after, Caddy's markdown support had promise, but agree with another commenter here that a few years ago astro.build started hitting a more interesting spot. In the middle ages between those, yay pandoc.