At WhatsApp, our engineers spend all their time fixing bugs, adding new features and ironing out all the little intricacies in our task of bringing rich, affordable, reliable messaging to every phone in the world. That's our product, and that's our passion. Your data isn't even in the picture. We are simply not interested in any of it.
Advertising isn't just the disruption of aesthetics, the insults to your intelligence and the interruption of your train of thought. At every company that sells ads, a significant portion of their engineering team spends their day tuning data mining, writing better code to collect all your personal data.