Okay, I get it. The interwebs is like the real world, but binary. We all want to play in it and feel safe. How come it hasn't taken off?
Let's take as a hypothetical example site X. If they have made a big enough name, I'll trust them. Why? perhaps because everyone else is. The power of the masses is such that even if we're all wrong, I feel that we can also all rebel at the same time and it will be okay than if I land on some random site that ends up stealing my identity and my cats.
I've just mentioned the fundamental problem: trust. How do you trust a service or a corporation that you cannot see, chase, yell at or run over when it pisses you off? After all, the people in customer service are but human employees, they are not the corporation. Those running the corporation are the closest thing, but up there who knows what's going on. Maybe they are nice and fix problems when they come up, or maybe they laugh at you and close your account.
This is the kind of situation that makes legitimate businesses not flourish: lack of trust.
Back to site X. It looks legit. Okay, that means someone knows how to keep up with web standards, etc. That's a good sign: dedication. It's no guarantee, however.
Let's say site X gets acquired by Y, a rogue company without any particular concern for the individuals involved. The site has OAuth and whateverconnect which allows your identity provider (say, Google or Facebook) to pull the plug on the service if they become rogue. Unfortunately, they can only prevent the rogue company to do evil on your behalf. It cannot prevent them from acquiring information from you: the information cannot be taken back.
This is the fundamental problem between real life (meatware) and virtual life (software): the model doesn't work.
Can you imagine walking into a coffee shop and automatically telling everyone in it your home address and phone number? That's the equivalent of an email address. Giving you a way to contact me back doesn't mean I have to give you a way to contact everyone I know.
Message to identity providers: allow people to see my avatar and nickname and to contact me through your service. That's it. Not my email address, not my contacts, not my fan clubs. It's okay if you aggregate my behavioral data along with everyone else's and profit from that information, as long as you protect my identity. That's your end of the deal in exchange for the information I choose to give you. I do buy stuff, I do need ads, and I understand you need to know about me to show me relevant stuff. Just don't sell my identity. Protect it. Your company depends on the trust that your users have.
Furthermore, knowing who I am doesn't mean you should know everything I do. In a way, that is equivalent to having someone follow you around, even if it's just to figure out what you like best. It's creepy and it's not because I'm doing something I'm ashamed of. It has to do with moods. If I'm in the mood for entertainment, I want to watch entertainment-related ads, not diapers. I don't need a reminder of what I should be doing instead, that's why I'm watching sports in the first place. That's why you shouldn't bundle my identity with my physical container. Each mood is a different account. Don't mix them together.
For the people implementing and designing these standards: pay close attention to how these interactions work in the physical world. After all, these protocols have been around for thousands of years and have evolved to their current state based on what works best: evolution and selection. Being smart is not a substitute for insight and patience, it's just shortsighted.
Before I climb off my soap box, let me add this tangential note: If I'm paying for insurance I don't just expect to get some money for my stolen motorcycle. I expect you to also not make me fill 30 forms that are just a seemingly random combination of the same information: claim number, name, address, lien holder, who did my service the last time... ugh. I get it, the more information the better but your forms are ridiculous. It is the modern equivalent of torture. Neither physical nor terrible, but very, very annoying. Pay attention to your job, there's people on the other side.
(off the soap box)
My duty as an engineer is to realize that what I create, other people consume. I can make their lives better or worse.
My duty as a human is to realize that my attitude is other people's experience of life, and that if something sucks it is because someone made it that way, even if not on purpose.
My footprint is someone else's path.