Org Mode keeps being pushed again and again, but honestly this title is one of the boldest claims I've seen about it. Just look at the document. It's a 400+kb HTML page of Emacs configurations, keybindings and other stuff that makes absolutely no sense unless you've been an avid Emacs user for years. Where is the Plain Text here? I see nothing of the sort. Sure, the output might resemble Plain Text, but it's clearly…
I agree. Why use Org Mode when, for example, Workflowy exists? The latter is robust to your hard drive failing and downloadable in plaintext, too. And it looks better. And you don't have to learn a billion key shortcuts with silly names like "yank" to use it.
I'm not claiming Org is a silver bullet, or even better than WorkFlowly or anything else people might use, but it definitely has it's place.