@david @tedcurran

I don't follow.

Just because I can have an identity that multiple platforms recognize doesn't mean I can't have more than one.

Heck, I have multiple email accounts for work and personal stuff, and both of them are recognized in multiple places around the web.

Same thing. Some people will have one identity that they use in one place, some people will have multiple identities that they use in multiple places, and people will also choose the other perturbations, just like they do with email accounts today.