Well, here comes the obligatory org-mode comment:
Org mode does most of that, too. And a lot more. And while you cannot use it in Github issues, you can in README files on Github.
Org mode does most of that, too. And a lot more. And while you cannot use it in Github issues, you can in README files on Github.
But yeah, to unlock the true power of org-mode you need emacs.
I can't help but feel like it would be a lot more widely accepted if they divided it in multiple projects each with their own goals and requirements.
The other barrier, of course, is that it doesn't really benefit existing Org mode users/developers.