I don't get why they won't just open source their main app code. It's already been mentioned, it's not like the concept is difficult or couldn't be cloned...it'

I don't get why they won't just open source their main app code. It's already been mentioned, it's not like the concept is difficult or couldn't be cloned...it's simply not practical for many reasons. But being able to have the code if really cool from an educational aspect.