Data-driven off the cliff. Keep in mind that most people in marketing are clueless about statistics, scientific method and any kind of rational reasoning. Same is true for their customers. You've got people knowing shit who write reports containing bullshit, which are read by people knowing shit, and since no one can actually verify if any of that is meaningful, everyone is happy and money flows around. And the people making tools for analytics actually exploit that too, since they're in competition with one another (see e.g. popular A/B testing tools encouraging you to reach a wrongful conclusion that your intervention worked - which makes you happier about using the tool). Advertising industry is rotten to the core.