I don't think this is the case. Rather, ad-blocking-blocking was the primary motivation, and the undoing of evilness is a byproduct that allows much better mark

I don't think this is the case. Rather, ad-blocking-blocking was the primary motivation, and the undoing of evilness is a byproduct that allows much better marketability. In reality, extensions are user-installed software. There is ALWAYS a risk with user-installed software on a PC. It's one thing if this is code webpages can automatically serve to you - then, the security is larger concern. But I, for example, don't see anyone trying to clean up Win32 for security's sake. The closest thing I can think of is Wayland, which is also for security. But - that's desktop wide, for absolutely all software.