Clarification: reveal.js supports markdown for individual slides. This project (Marp) allows you to write your whole presentation in a single markdown document.
(Using just "---" to separate slides instead of repeating:
<section data-markdown>
<script type="text/template">
slide markdown goes here
</script>
</section>
(Using just "---" to separate slides instead of repeating: <section data-markdown> <script type="text/template"> slide markdown goes here </script> </section>
...seems like a productivity win IMO)