Maybe this is a bit off topic, but I think trjordan's point was really that the tracking/retargeting industry is productized though. Google, Facebook and others ultimately serve as platforms for ads as well as providing tracking software. Meanwhile, companies like Marketo provide pretty advanced tracking/attribution data to the companies that use them. They specifically enable tying device IDs harvested through mobile apps that use their tracking SDKs to be linked with other browsing and email behavior to build extensively customized ad campaigns targeted at specific behavior patterns.