Given the history of Google's stance towards privacy and tracking, I think it's naïve to assume technical reasons.

It may have been ok to fall for that argument for 10 years, but after AMP, manifestv3, android's location log disaster, the recording of wifi names and countless lawsuits across the globe, it seems that the resource of good faith assumptions has been depleted. Some may even say that trusting google (the corporation) to act on technical or altruistic reasons is delusional.