While I agree with your points about the failures of Zynga’s approach, I’m not sure what any of this has to do with product management. The role of a product manager is to discover and quantify market problems and then ensure that the best possible solution for those problems is delivered to the market. I don’t know any decent product managers who would willingly ship inconsistent or non-holistic solutions to the market. Product Managers care deeply about things like usability, user-journey, information hierarchy and brand consistency.
Data is just one tool in the arsenal or product manager and UX designers. It’s just one input amongst many that can be used to aid decision making. Any PM worth their salt will use a mixture of quantitative (data, a/b tests) and qualitative (customer interviews, usability tests) inputs when optimizing a product.
This problem you’re articulating about the issues at Zynga seem more of an issue of higher level product direction/strategy.