Ben Thompson's Stratechery mentioned in a recently daily update he thought Adobe's acquisition of Omniture long ago was a mistake (due to
Google & Facebook owning the online ad market) and they've had to sort of paper over it by continuously buying more & more of what eventually amounted to an entire ad tech stack. Owning the underlying OS for the merchant is sort of the logical end game from there.
With GDPR active in a couple days &
Amazon aggressively entering the ad network game to display ads across the web, this is perhaps one of the better ways to try to stay competitive in light of an increasing share of ecommerce-related ads being driven by ad retargeting. For broad-based ad networks which are not brand-driven, owning the cookie is going to be vital to staying competitive with the duopoly & the growth of Amazon. Hosting the content gives one a leg up on the attribution front when multiple ad networks want to claim they drove a particular conversion.
It might be sunk cost fallacy, but not trying to keep that piece of the business competitive could harm the narrative behind the stock. And loss of narrative control tied to questioning management investments is probably not so good when a stock's P/E is close to 60 and the market cap is almost $120 billion.
