That's only a requirement if the site you visit wants to track you. They could simply not track you, and then they wouldn't have to show anything.
The choice given by gdpr is, roughly, either: no tracking OR do track but ask for consent.
Those websites doing the cookie walls should have taken the hint to simply not do tracking. Instead, they chose to be annoying.
Yes, but that's the ePrivacy directive, not the GDPR.
Yes, it makes it very obvious which sites are trying to track my activity and should be avoided and rewards sites that don't by making it obvious that they aren't.