Well Rails doesn't scale, or at least it didn't at the time when Twitter jumped ship a few years ago. Could argue that for the current earnings report to have

Well Rails doesn't scale, or at least it didn't at the time when Twitter jumped ship a few years ago. Could argue that for the current earnings report to have even been possible, they had to move away from Rails; otherwise the user base could not have grown to what it is today. Saying that, Rails' scaling story has likely improved since 2009/2010, I believe Github and other high traffic sites currently use Rails. For Twitter it was too late. Only high profile company I've heard of that left Rails for greener pastures.