Facebook internally considers the social network to be their major asset, not their technology. This is very different from other companies, for example Google

Facebook internally considers the social network to be their major asset, not their technology. This is very different from other companies, for example Google who build proprietary technology, and generally keeps them that way, but may give away things other than core technology. Any investment in open technologies or internal (which can be publicly released) technology which make the network effect stronger is considered important. (I'm an ex-FB engineer and program manager)