As first reported in The Guardian, during the launch event, the social media CEO was asked why Facebook had chosen to partner with Microsoft, rather than Google, to create and launch the new feature, and he explained that it was simply a question of privacy.
Microsoft was willing to make this change and that is why the two companies have been in partnership since 2010.
"I think the main thing is about when people share something on Facebook, we want to give them not only the ability to broadcast something out but also change their privacy settings later and take the content down. That requires incredibly quick updating ... We need that content to be gone immediately ... You need infrastructure that can support that and that takes a lot of commitment from the partner. Microsoft was more willing to do things that were specific to Facebook," said Zuckerberg of the decision.