A year of Windows kernel font fuzzing #1: the results

Humor me here, I'm just a dumb ol' linux guy, with no real Windows programming experience at all. Truly.

The title of this article caught my eye: "kernel font fuzzing". Seems that both Silbershatz and Tanenbaum missed an entire chapter worth of kernel-related material: font handling. But if I get down off my linux high horse, I can see that the Win32 subsystem should have font handling. The question I have is: why does the kernel end up doing that? Don't the kernel programmers end up putting huge amounts of code in Ring 0/kernel space that really shouldn't be there? Doesn't putting font handling in the kernel make for slow/difficult development? Honestly, I don't get it. Why is font handling in the Windows kernel?