their theory is that the balls are made of tougher rubber than inner tubes, so you don't get punctures in the first place. Overlanding on an overloaded bike, I never altered my tyre pressures (except when blowing them up again after punctures), seemed pointless.
They might not be ideal for the more enthusiastic dune-lovers. But (if they work, and if you can bear the cost) they might be great for people who want puncture security, at the expense of being able to meddle with tyre pressures. Then again, Deserts filled with Ultraseal seems to work, and would be cheaper.