Anyone who is really slammed (pulled locking collars/perches or collars all the way down) isn't running preload. Stiffer springs keep the fender from contacting the wheel not preloading the springs. Preload only makes the suspension behave more consistently and bounce less over bumps at cruising speeds. I haven't seen too many coilovers, at least for a mazda3, that go to the ground with preload still on the springs. With my BC coilovers and 135mm 10k springs the car was slammed as hell but when I added preload for winter mode it raised the car up a solid 1.5-2".