No-no, this is not about passion. When one joins Facebook this does not mean he or she works on "social networking", it means he or she works on a tiny portion of a massive Facebook's codebase, implementing, say, a layout of a targeted ad for Chinese users.

I don't want to say anything is wrong with Facebook in this situation, it's just a company with a huge product and 7000+ employees. You are almost guaranteed to be re-inventing the wheel "Facebook way" there.