It would be great if web browsers had a way to actually indicate the user's preference of typeface, but what we've actually got is the browser's preference, and the browsers almost all have chosen really terrible default typefaces. It's fine to say "just use the default" for Mac users who get a decent default, but then the poor windows users have to suffer through some terrible serif.

The users who actually know how to change the default font also know how to use stylish.