Why you should not follow Shopify's holiday strategies

Unlike other communities here we speak about real life marketers issues and not the generic text book concepts.
The one another real issue which needs to addressed at the moment is,

Does the algorithm of the ad platforms still works the way they used to be in the pre-iOS'14 era?

To succeed in this BFCM and holiday season ad campaigns, the tech giants Google & FB itself urges the marketers to use their own first-party data rather than adhering to the conventional advertising guidelines and recommendations.