I view Facebook and Twitter as unnecessary playgounds for me. My objective is to limit my channels of communication so i don't have to micromanage all these unproductive services. I don't see why you'd want to limit your user base like this.
He's saying Twitter and Facebook are becoming, for today, what email was 10 years ago. You may have seen email as "an unproductive service" back then, because why would you email when you could call and write letters?
Then sites started requiring emails to sign up - and you signed up anyway. Why wouldn't sites just let you register through snail mail? They're limiting their user base!
In all seriousness, Twitter and Facebook are trending, and you might as well adopt them. Not doing so would strike me as a bit of technological ignorance.
I see this fairly often. Why not make an account solely for auth/signup on these sites. Most of the time people who say this talk about how they don't have the time, don't want to be on social media, concerns about privacy, etc. If you have an account just for logging in to FB Connect, it seems like the problems are alleviated.
I think the concern here is that, even if you make an account specifically for the purpose of authenticating to other websites, you're still telling Facebook, Google, Twitter... which websites you're signing up on, which they of course have an interest in knowing so that they can better profile you as a user.
Note: I have accounts on these sites and actively use them, just my guess as to other peoples' rationale behind not getting an account.
Implement Facebook Connect: 5 minutes. Implement own login system (with login screen, register screen, forgot your password screen, CAPTCHA, and making sure BCrypt is working properly): X hours. I'll do the former, even if it annoys 0.1% of possible users.