We use this to 100% accurately track all of our Woolworth's gift card purchases. The method is simple we are given an encrypted token by Woolworth's which we pass in every click. Woolworth's identify the token as a trusted source and displays exactly the content that is relevant to the consumer, the consumer then purchases and Woolworth's do a server to server call to pass the data directly into our database in real time. No (3rd party) cookies, no discrepancy, no problem. Now I am not saying every traffic source requires this type of integration as that would be costly but if one site is delivering 1% of your sales then it would make sense to generate a proper tracking system that is 100% more robust than cookies. The consumer can then take the actions advertisers are hoping for and that marketers can then correctly measure their campaign performance. The problems with (3rd party) cookies They can be blocked by almost any browser plugin, virus software, and Ad Blocker They can be deleted at any time They are not trusted by users They can be corrupted They are antiquated it is 2016 and I can not think of one significant improvement in cookie tracking or reliability