It does seem to be kinda the same thing - "communicate your privacy preferences [from] your device [to] websites or apps. You could then choose whether you want to accept, refuse, or limit tracking."

But is there not a way for these advertising/tracking cookies to be genuinely blocked by the browser?

Would it not be as simple as treating every new tab as if it were opened in a private/incognito window? Well, with the slight difference that only first party cookies would be allowed to persist across sessions - all 3rd party cookies would be created new, and destroyed at the end of the session.