It's pretty silly to claim that one way or the other is "obviously" wrong. A primary objective of defaults on the web is to never hide content; if "width" specifies the width of the content itself (i.e. box-sizing: content-box), when I say "div { width: 100px }" and put an image that's 100px in that div, I never crop/lose content. You can argue one way or the other, but neither is "obviously" more correct.