My (actuarial) read on this is that pre-Microsoft GitHub acknowledged that the complexity inherent in their technology stack imparted a lot of change risk, and that probably informed their decisions around shipping new features.

My (not-so-actuarial 1990's-experience-colored) feeling is that this is Microsoft doing what Microsoft does best, namely including a lot of seemingly compelling features in a product to get people hooked and to keep competitors in a position of trying to keep up.