Accessibility: Bing is Doing it Wrong

Bing is my default search engine because, well, rewards. It's not the best search engine as such and I often end up wandering off elsewhere while researching to actually find what I'm looking for, but hey, it gives me stuff in return for using it. But in addition to not being the best search engine as such, Microsoft is now making it harder to use (if you want to participate in the rewards program). From a December 2 email:

On February 5th, Bing Rewards will no longer support Facebook as a sign-in option. To keep earning credits -- and get more ways to earn exclusive offers -- transfer to a Microsoft account.

This is exactly 180 degrees ass-backward from how things should be. Service login convergence is the order of the day. Users -- including me -- are getting more and more accustomed to being able to sign in pretty much anywhere using credentials from pretty much any major service (Facebook, Twitter, Google, et. al) via the 0Auth standard.

Presumably the purpose of Bing Rewards is to bring in new users and keep them there. Why would Microsoft go out of its way to make the program harder to enroll in, harder to log into, harder to benefit from?

It's. Just. Dumb.