> for projects at Github's scale it's rarely a code logic/framework-level blunder that's taking the service down. It's generally a cascade of failures in things like multiple database systems, auto-scaling, dns/caching, etc.

This is just guessing. You can't honestly tell what is causing the issue.

Twitter too was on Rails in the initial days which helped it took off, and then realised they need to move to JVM(Scala) to scaled and they have been performing brilliantly since then.

Now, that MS has bought them, why don't they use the brilliant tech MS has (.NET, .NET Core) and be more reliable?