Semi-intentional compartmentalization could explain it.

  Ads: we could increase revenue if we had access to WhatsApp data, but that's Product and Legal's call.

  Product: Ads asked us to access WhatsApp data, but we're just facilitating between them and Legal.

  Legal: Ads and Product asked us to change the policy to allow access to WhatsApp data.

Nobody being willfully malicious, just not asking certain questions, and the gaps between departments obfuscate the whole thing.