X had no facility for antialiasing fonts until about two years ago. Before that, all fonts were 1-bit rendered, and that was defined by the spec. I haven't looked into what the new stuff does, but it's implemented as an extension to the X protocol, not as a replacement for the standard font rendering. As such, programs have to be specifically built to use the new font renderer.

Of course, I haven't looked at this in a while and could be wrong.