I see some reasons to do so. You can write a blog in Markdown and generate your own static website with it, you could write a diary in Markdown, which I do, or

I see some reasons to do so. You can write a blog in Markdown and generate your own static website with it, you could write a diary in Markdown, which I do, or you could take notes of code implementation, which could require LaTEX for nice mathematics and code fences to organize small chunks of code.