I think everyone focuses on the "light" instead of the "fast." Every reasonable person knows what their limits are. The way I see it is the faster you are- the lighter you can go. If you are slow person, than perhaps going light means taking the lightest tent. If your fast- perhaps its means taking no tent at all. But if your as slow as hell don't think that not taking bivy gear will make you move ten times faster.
Also, the "speed is safety" mantrum, in my opinion, is great for routes with high objective danger. But for the routes that most everybody does around here, going superfast (i.e. simul-climbing, soloing, or going without bivy gear) is most likely slightly more dangerous than taking a regular approach to it. Part of "Light and Fast" tactics is an obvious increase in the risk level.