Heh, that's very much like the old "... and nothing of value was lost" then.
- Cookies weren't doing a whole lot for them to begin with, and removing their use had negligible impact.
- The other work their marketing department did to try and compensate for discontinuation of cookie usage interfered with the test, making the results useless for evaluating the value of cookies.
I'm leaning towards the second one based on the response above you.
If the point is to quantify the value of cookies then you need to measure that as an independent variable. Attempting to compensate with other actions, each of which you also don't know the independent value of, means you will be unable to quantify the true value of cookies or the value of your other actions.
What if none of the tools they're using, including cookies, provide any measurable value? How would you know? What if the value of cookies (X) and item A is positive in terms of impact, but B and C are both negative, but not enough to offset A so it comes out in a wash?
Laws like ePrivacy in the EU do indeed have specific provisions regarding cookies but e.g. the GDPR is much broader than that and would still apply. How truthful is it that eliminating cookies is motivated by a strong stance on privacy rather than just getting a head start in marketing instead of having to scramble when Google pulls the plug? It doesn't sound like you reduced the tracking and behavioral analysis beyond what was technically unavoidable?
It's incredibly hard to tell. For us the goal of eliminating Cookies was important given the stance we have on privacy so everything went from there. The folks working in marketing for sure were not happy with the directive as it makes their job much harder.
But the world is still spinning, even without cookies. That's enough to call this a success.