Maybe we don't need so many "light" markup languages. Writing html directly is as easy as writing any markup language if you have a good html editor. I have been taking notes with html-notepad (https://html-notepad.com/) for a long time and the writing experience is much more enjoyable than writing md, rst or emacs org mode (I only tried these three). Taking notes with html doesn't mean you have to write verbose html tags or the html tags would clutter the edit area. The html-notepad is a WYSIWYG editor which means what you see is a rendered html page when you are editing. There are keyboard shortcuts for oft-used elements like header1~6, lists, code and so on, and you could edit the html source if you like. Although the html-notepad has some flaws and lacks some really useful function (like search and replace), it's definitly a very convenient tool for me.