Sooner or later every single company that builds their own software comes to implementing some kind of generalized build & deploy system
. While meeting the need, such a system does not add any competitive advantage to the core business. It is like if each company will start creating their own programming languages: it could be made highly optimized for a particular business, but maintaining one sucks in more money that it generates. And don't forget the people around it: how much expertise is preserved when developers rotate or simply resign? What kind of support does such a system gets?