The point of the cookie warning was not to give users the option to disable cookies (although giving the option to users that are not familiar with their UA is

The point of the cookie warning was not to give users the option to disable cookies (although giving the option to users that are not familiar with their UA is also a nice side effect). The point was to force websites using cookies for "dubious" tracking purposes to be forced to show the banner as a mark of shame so that users would naturally migrate to websites not spying on their users and therefore not showing such banners. Obviously, this universe being the dystopia that it is, every website started showing these banners overnight and users started ignoring them anyway. If you just enforce all browsers to ignore cookies period, then you have another X-Do-Not-Track-Me scenario (or whatever it was called), where everyone just sets this flag and therefore tracking continues, just using other methods.