Because of the fundamental asymmetry in the law: advertising+tracking don't require AML/KYC, cryptocurrencies (mostly) do.
If your users pay you with their attention or tracking data, you're not required to verify their identities, ask them if they're terrorists, store copies of their passports in some hacker-magnet database, or any of that.
If your users pay you with cryptocurrencies you have to do all of that.
The problem isn't a business problem or a technological problem, it's a regulatory problem. This outrageous double standard is massively subsidizing the adtech-surveillance monster. Require AML/KYC be performed on users before ads can be shown to them, and if ads are shown or data collected without AML/KYC, impose the same "corporate death penalty" allowed for AML/KYC failures. Or else eliminate AML/KYC for cryptocurrencies.