These metrics are anonymized. This is for A/B testing and it's common practice to optimize onboarding flow based on where users came from. Not stalking at all. It's literally called Growth and companies have entire teams dedicated to optimizing onboarding.

>> Your metric should be whether you are making more $$$ with the ads than without.

Not if you have different conversion rates based upon where your customers come from (and want to improve conversation rates by A/B testing different customer segments); then the metric you suggest is bad. You have an extra variable which is organic acquisition so you can't optimize as well.

I don't think it's stalking. As mentioned, it's anon'; In addition, $ isn't always the KPI you are looking at. If, for example, you want to see what source of traffic brings the most retained users in order to invest your marketing budget in the right place? Totally legit IMHO.