[scubbo]

OK - so instead of cookies storing information on who you are and sending that back to the service, you instead have your browser telling the service who you are and the service storing that information on you?

I'm still not seeing the advantage. This isn't me arguing with you and telling you that you're wrong - I just genuinely don't see the difference and would like to understand better. This hypothetical service will still have the same amount of information on you either way (just stored service-side rather than in cookies), right? Unless you're claiming that the service wouldn't associate your various sessions with one another, which seems both incorrect (they certainly would, if they possibly can - as you say, via IP address, etc.) and undesirable (almost all moderately-sized-or-larger web services would feature some kind of persistent settings, at least).