It's an act of self-protection. I'm not anti-advertising. I'm anti-running-untrusted-software on my property. If they had stuck to adwords and static images with no invasive tracking I'd let their ads run. But the surveillance capitalists can't help themselves and want to run their 50MB spyware payload on my computer. I say no to that garbage.
"I'll run the arbitrary code you send me if you acknowledge that you are legally liable if it turns out to be a virus or a scam... No? Why won't you take that deal?"
Correct. Google had initially a good program that was based on keywords and non-intrusive ads. They killed that in the pursuit of more profits.
Precisely this. The industry has themselves to blame.