Facebook could reach people not even thinking about a job, yet could be convinced to apply for the chance at a higher salary. That’s the same reason Facebook has been able to build giant brand and performance advertising businesses despite Google’s traditional dominance. You might search on Google when you know what you want to buy, or on LinkedIn if you know you want a job, and their ads can help with demand fulfillment. Facebook offers demand generation, drumming up interest people didn’t know they had.
Source : Facebook threatens LinkedIn with job opening features | TechCrunch