"Global mass market" meaning? try to have a more focused definition for your audience. It all depends on the audience in general. For example, if you're making an e-commerce site, you wouldn't want to limit it to just folks who have a twitter/facebook account...but then again that depends on what you're selling. If however you were making some sort of a social app that leverages people's connections already, then there's really no need to use any other authentication strategy than OAUTH. So I'd say think about your target audience and make your decision.