Yeah, I don't know how it went down, but I also know exactly how it went down:

Microsoft Execs: Everyone needs to move to Azure!

GitHub developers: But Azure is not gonna be able to handle our load, we literally have our own data centers!

Microsoft Execs: Sure, but you're Microsoft now, please publish blog post about how in half a year you'll be 100% on Azure.

Few months later...

GitHub Developer: We've tried our best, users are leaving in droves and Azure can't keep up!

Microsoft Execs: Ok fine, you can use something else too, but only if you mainly use Azure and continue publishing blog posts about how great Azure is.