Markdown is for keeping things simple.
There's plenty of of "proper" markup languages and full programming languages to actually write code in.
Why do we need a hybrid program like this, which is not as simple as pure markup, and is not as powerful as a proper templating language?
I personally just run markdown -> HTML/CSS -> python templating (Jinja or something) -> PDF/HTML
As a dev, I find this works the best for me. But I also cannot imagine that learning Quarkdown would improve my workflow meaningfully, and I also cannot imagine recommending someone learn such a niche product instead of having them learn HTML/CSS and Python (Jinja if they need fancy). Seems like a comparable amount of effort.