Metal fatigue is the elephant in the room here. The stresses on the lug studs are different with spacers no matter which way you skin the cat. If/when the lug studs start to yield, and with spacers they can start to yield over time even with proper torque applied, you will have very little time to catch and address it before complete failure. It doesn't always present itself in a way that is easily detectable like vibrations. Who is actually pulling the wheels to properly check both sets of studs on a regular basis? I'm willing to bet most do not, and certainly not enough to catch it in time.
I don't think anyone is saying it won't work. It's just inherently risky, even when installed correctly. There is a reason the reputable tire shops won't touch them. Again, go for it if you understand the risks. As a kid, I would have done it without thinking twice. Today, with my family in the truck and about 7" taller than stock on 38s, not a chance in hell. Everyone's risk tolerance is different.