It's trying to ease the problems surrounding contextual overrides. Having color="red" and other inline styles is a bad design pattern, but AM only superficiall

It's trying to ease the problems surrounding contextual overrides. Having color="red" and other inline styles is a bad design pattern, but AM only superficially resembles it in that it uses attributes. Whether you give an element the attribute of class="nav" or just am-nav, it's accomplishing the same thing: defining that it's a "nav" element for purposes of styling.