Some sites try. It's an unsolvable problem, like DRM. My machine, my rendering rules. Only way around it is restricted clients, like consoles and iPhones and so on. Or maybe Intel SGX, which allows remote attestation of running specific code.

And ad companies brought this on themselves by being idiotic and annoying. Even Google is as bad as the others in the 90s. On mobile apps, I get scammy "virus scan now" or "clean phone fast" with blinking yellow and red. They link to the Google Play store, to install some app that requires all permissions.