Google's latest Off The Record podcast was titled Markdown vs HTML with John Mueller and Martin Splitt talking about the use cases for both. In short, both said that when it comes to SEO and Search, that HTML is the standard and what is needed. Markdown files do not give you any benefit for SEO purposes.
Here is the podcast that you can listen to yourself:
John said at the end, to sum it up, "for all of the SEO-related things and discovery of content, a normal HTML website is like..." Basically, what you need. He said earlier, "the generic SEO angle of how do I find a website that sells me a photograph is almost going to be completely bound to HTML pages and normal web pages."
Web crawlers and search engines have decades of practice processing standard HTML. Extracting plain text from HTML is already a trivial task for automated systems and web libraries. Publishing normal HTML pages is the primary prerequisite for your content to be crawled, indexed, and discovered by both traditional search engines and AI systems.
They also implied that you should not create separate, parallel Markdown versions of your website solely to cater to Large Language Models (LLMs). Maintaining two versions of a site doubles the workload and significantly increases technical complexity. If a hidden "LLM version" of a page breaks, human users will never see it, meaning the error will likely go unreported and automated systems might blindly index the broken page.
That is not to say markdown does not have a purpose, it does. It is a good episode to listen to. Or you can read the transcript PDF over here.
Forum discussion at X.
