They want their own platform so they can do whatever they want on their apps. They are playing the long game. Read zuck's VR vision letter. He lays it all out:
Meta is the last company in the world that I would allow to have direct access to my gaze tracking data.
The only thing that I can imagine that would be more privacy invasive would be a device that directly reads your brain waves while you are exposed to different stimuli.
I feel exactly the same, but I think we’re very much in the minority with that perspective compared to most consumers, so they could still sell like gangbusters.
And on that note I can’t wait to see Meta’s answer to Neuralink!