It's a CIYA thing as mentioned above. The same reason Rancho doesn't officially make lift kits taller than 4" and many suspension lift manufacturors don't recommend the use of body lifts in conjunction with their suspension lifts...aside from their own body lifts of course.
Spidertrax is still kind of a small company that makes niche market stuff. Say someone gets in an accident and in a court of law they get blamed for it. Some sympathetic jury gives the plantiff a couple million dollars...bye bye Spidertrax...
Now simply putting that label on the box clears Spidertrax of pretty much all liability. You die on the road, all they have to do is say, "we said not to..."
