Those are the best examples of material design? Most of them are phone screenshots, higher than they're wide, on a blah background. The "material design" thing is supposed to be about dynamic effects. You click on things and they ripple. If the site let you go to the actual site or app being described, that would be more interesting. Or they showcased the material effects on their own site.
Everybody has solid-color rectangles now. They're boring.