I have a real problem with "preloading" any bearing on a bike. Preloading means that all clearance is removed, and then the bearing is tighten a certain amount more. That means the bearing and the races are deforming, and will lead to early failure.

Whats even worse here is that if the work is done in a cool shop or basement, and then the bike is taken out in the heat of the day, that damage will occur even sooner. Front wheel bearing are a great example of what can happen with "preload". With the wheel off the bike if the bearing is preloaded, and then the wheel is put on the bike and the quick release is tightened, the bearing ends up with almost a bind, and quaranteeing quick failure.

Proper adjustment mean all play is removed, or better yet all but only a bare minimum of play is removed. Im talking half a thousandth here.

A great example here is wheel bearings on cars. The adjusting nut is tightened up to where all play and maybe to where there is a slight preload, THEN the nut is backed off untill the cotter key can be pushed thru its hole and bent over.