If only Microsoft hadn't chosen to use the code-name Hailstorm for its authentication proposal back in the days (and generally had a better image and a more open approach etc). Would have alleviated a lot of the pain earlier.
Hailstorm was always just a very early version of what today we see in OAuth/OpenID Connect.
The one that we should be truly sad didn't connect with enterprises/consumers was Vista-era CardSpace (http://en.wikipedia.org/wiki/Windows_CardSpace). That was an early play at what today we are finally seeing in FIDO / Webauthn standards, with a rather good UX to go with it (using the visual metaphor of plastic cards/credit cards for PKI identities).
Albeit with the usual problems that that version of Microsoft only supported Internet Explorer on Windows Vista+. The standards behind it (PKI and SAML) should have been interoperable enough that other implementations would have been possible, but the Microsoft of that era wouldn't have been the one to build it. Had they supported XP, and had they supported Firefox/Chrome maybe more people would have heard about CardSpace at all.
ETA: Wikipedia points out it did ship for XP at least with the giant .NET Framework 3.0 upgrade that almost no one actually installed on XP. I had forgot that.
Hailstorm wasn't really the same thing. It positioned Microsoft as a centralized identity provider, with MS holding all the user data and everyone else just connecting to proprietary Microsoft online services to check if the user was who they said they were. Kind of like Facebook Login, but built around 2000s-era-trendy technologies like XML and SOAP instead of JavaScript and JSON.
It's hard to see how Hailstorm wouldn't have run into the same issues people have today with Facebook Login, the big one being that it's maybe not awesome to have a gigantic, notoriously ethically-challenged competitor sitting directly between you and your users.
