Their house, their rules. I get and approve of, the benefits of open source projects. But, I also get, and approve of proprietary for-profit ventures. In an open, robust competitive ecosystem, both products can do great things and complement each other. For example, Linux does what it does very very well. And, Microsoft and Apple (love them or hate them) have been pretty successful at the private, proprietary for-profit angle. Linux makes Microsoft and Apple better and more competitive. Apple and Microsoft make Linux better.
Would the world be better off with just Apple? Or just Linux?