How do you activate the top system menu bar, to navigate through it via keyboard only? I always thought Mac designers were retarded for not making this critica

How do you activate the top system menu bar, to navigate through it via keyboard only? I always thought Mac designers were retarded for not making this critical feature obvious. Another peeve is the lack of dedicated keyboard keys. Like the printscreen key. On Mac you have to press something like Command-shift-4. Often times I notice, the Mac designers try to simplify things for the sake of design, but they end up making the damn thing harder to use.