I can definitely see how it could be more useful, but I don’t agree that the actual factor of this increase in productivity is infinite. Maybe a factor of 3 to 5.
Having used duckduckgo for a few years, which does not personalize results by default, I don't think it's even that much. More like, a factor of 3-5 on select searches and not at all (occasionally even negative) on others.
I thought it was fairly clear that I was being hyperbolic. I don't see how you would decide what that factor actually is, but to me, anonymised results across the population of gogoele search are often going to be useless, so if the addition of any metadata gives them any use whatsoever, then it's infinitely useful than a completely useless query.
That said, you're arguing semantics about the relative worth of the results, even if it is a factor of 5, that is more useful, and the answer to OPs question of is tracking useful is "yes".