Issues with Quora aside, I think it's actually coming from people inside the bubble of startups/design/ux who want to complain without actually testing things.
I often show my wife sites/apps that might interest her. I've never heard her complain about creating an account (either with email/pw or facebook). If they drip-spam her, she'll unsubscribe. She's not a designer or hacker–just a normal 30-something, slightly-entrepreneurial, facebook-gmail-mac-using wife-mom.