Not at all true. My girlfriend, a Stanford graduate in mechanical engineering, used MOOCs to do a career transition from product design to computational disease research. She would never have been hired without the skills she learned online.
I disagree. I can't quantify it, but taking a few impressive-sounding (and -being) courses makes you look good in employers' eyes. It shows you to be a self-driven learner who tangles with hard stuff. At least somewhat. But you're right in that it's soft; a hint, rather than a certification.
It's like reading a book: No one else give a shit.
I would add that for most jobs knowing more than the basics from a course, and often not even that, isn't useful.