There was a belief for a time that consumers no longer cared about privacy, that the millennial generation preferred to share everything, and harvesting data was fine because the concept of privacy was antiquated.

What surprised a lot of tech execs was that when people understood how much data was collected they got creeped out and when given the option to opt-out of data collection they agreed at very high rates.

Apple's move to limit in-app tracking was genius because any lawsuit from FB or similar is counter-productive - consumers are given the option and they opt out at 99%. Suing Apple to force them to let FB track consumers would be a PR disaster.