Of concern is that they are using a third party affiliate network. That means tracking and selling you.
Besides, all affiliate networks are (by definition) third party. In many cases, it's just not worthwhile for the merchant/advertiser to setup a custom tracking and billing solution.
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Oh wait, they instead decide to tunnel all clicks through their own infrastructure? At massive cost and complexity? I wonder why they decided on this implementation, huh.
So many big brands are running multiple tags taking down more client info than Google Analytics - and then asking why pages are taking 5s+ to render