With acquisitions, Facebook has generally left the acquired company mostly alone (if it's big and successful already). Instagram, Occulus and WhatsApp as examples. Instagram competes with Facebook in some ways, too, but it's still separate.
Is collecting data the goal, or simply diversification?
My theory is that Facebook (the company) is preparing for the day when Facebook (the website) goes the way of Friendster and Myspace, and they're attempting to have other lines of business when that happens.
Their goal is more data, not less competition.