But what pixel perfect means in fact? That it looks as it was supposed to. If I'm a designer and design something which looks perfect, do I want a coder to alter this perfect look to something ugly?
Ideally pixel perfect is replaced with "looks perfect" and designer works closely with coder to achieve perfect look on various devices and resolutions. But I don't think coder should make assumptions how the coded design can differentiate from the original design (unless they have very good aesthetics feeling).