> Why not make the ordering matter? If you just write the sources in
> decreasing dpi order, you can still just pick the first one you can
> successfully render.
But "the first one you can successfully render" isn't what image-set()
is about. The author really doesn't know which asset would be best—that
depends on a variety of factors. It might even differ in the same UA on
the same device (e.g. asset choice based on current page zoom). Asset
choice based on a scale factor isn't (solely) about device resolution
and, well, bigger isn't always better.
This is really different from image()'s directionality annotations.
Directionality annotations don't affect which asset you choose, they
only affect whether or not you flip the asset after you've chosen it.