The biggest problem here is the use of the term "de-power". Kites don't have throttles! I blame the kite companies for all the ignorance out there on this topic because it was them that have been marketing kites with de-power.
Kites are designed to fly at a particular angle while holding a set shape. Trimming a kite is nothing more than keeping the AOA, and shape while keeping the bar in a comfortable spot. If your using your trim strap to "de-power" your kite all your doing is messing up the way it handles and flies. It's the same with people over sheeting for power and not being able to get upwind even though they think they have power.