Many people want to do many things, problem is do we agree as society it is ok, considering all the implications.

I personally find the commercial targeting extremely poor. I look for things to buy and I get stupid ads which don't fit, or I bought the things and still bombarded with the ad for the same thing.

But data collection can be used by far more nefarious purposes, like political manipulation (already happening). So yes, I am willing to give up some percentage points in optimizing the commercial and advertisement process (for your example, wait for 2 weeks and check for the actual sales volume difference) to prevent other issues.