Curious how well understood the mechanics are of this. I've been fascinated by how clever the whole model works. They know revenue growth needs to outpace their ability to increase available ad space (so user growth or attention growth). So they are heavily reliant on data to improve ad targeting so they can drive more conversion per ad impression.
The power of the ad auction model is that 100% of the improved efficiency of ad targeting is translated to revenue for Facebook. Advertisers will pay $X for a conversion in their ROI calculations - so Facebook will get the maximum amount the market will pay a certain for a given conversion. Advertisers are actually a little worst off as targeting gets better - the conversion cost stays the same and the number of impressions goes down.
To keep growing revenue at this pace, Facebook needs to continually feed the beast with better and better data so they can squeeze more and more conversions out of their existing ad space.
The only other two ways to grow revenue is more users and more time from users. Which is getting tougher and tougher. That's why this Apple fight is so important to Facebook - it's really their lifeblood right now.