It doesn't necessarily have to be about size. The goal is to let the browser paint the above-the-fold content without any external round-trips. Using the least

It doesn't necessarily have to be about size. The goal is to let the browser paint the above-the-fold content without any external round-trips. Using the least possible seams sensible, especially if you do it on every page. This lets caching work as intended for the majority of the CSS.