Don't all electromagnetic waves travel at fixed speeds?

I know sound and light do, since they both exhibit Doppler effects. So, why all the fuss over the fact that light travels at a fixed speed? Why assume, simply because light, like all other wave forms, travels at a fixed speed, that nothing can travel faster than light? Just because Einstein was obsessed with light, doesn't mean everyone has to be. Possibly, the reason for this obsession is that "nothing" exists in space, and light still travels in it. But, we seem to be aware, now, of a kind of "quark soup" of elementary particles in space, that may, possibly, explain the mechanism of this motion, someday.