jevgeni made an excellent point and actually articulated his concern. Open source has absolutely nothing to do with how Google is tracking users here, and not only are there major parts in the Android ecosystem which are not open source but even more importantly, the case at hand obviously shows that is irrelevant whether something might be open source or not.
And that does not take into account that the vast majority of people do not run any version that has such features removed, as you hinted. If anything most users run versions which have additional stuff added (Samsung, etc.).
Once all of that is not true anymore you might have got a point, until then it is jevgeni who hit it on the head.