I haven't come across a scenario where openid did not work. Care to elaborate? I think of openid as the git of the login systems. Elegant in it's simplicity

I haven't come across a scenario where openid did not work. Care to elaborate? I think of openid as the git of the login systems. Elegant in it's simplicity but comes with a minor learning curve and the benefits of climbing the learning curve far outweigh the cost of doing so. And very much like git, it takes 15 minutes to get over the learning curve if you are good with google and/or have some guidance.