It's the same thought process behind 90% of the things we do that people hate Mozilla for. People think Mozilla is pure and 100% ideal by whatever standards that they make up themselves, but the truth is that Mozilla is _pragmatic_. Sometimes we do things that aren't great because to do so otherwise would hurt the greater mission.
For example, we don't exist to create 100% open source software 100% of the time. Instead, we _strongly_ believe what we say in our manifesto: "Free and open source software promotes the development of the Internet as a public resource." Sometimes, mostly when we're working with a partner (like a phone company) who can offer us significant leverage, we write some code that isn't immediately made public, and _that's okay_. Our end goal isn't to put more open source software in the world, it's to further the internet as a global public resource.
(Mozilla is also so diverse and disjointed that sweeping generalizations like the ones I just made are completely inaccurate. We make mistakes and we make bad choices. Mozilla is more like several different companies that happen to share the same name.)