The question may be better stated, "Why is the 4 ohm number so large?" The 4 Ohm number is so large because Class-I is not fundamentally voltage limited, unlike ALL other amplifier designs available on the market. Competitive amplifier designs require complicated multi-level (Class-H) supplies, which limit the voltage available to the output under low impedance loads. This multiple step supply topology lends itself to the typical power matrix.
The down side of Class-H is that if the program material asks for a peak higher then the rail voltage limit the amplifier will distort. In other words, headroom is limited. Class-I does not exhibit this limitation. 200V is always available to all loads. As a result the amplifier is capable of producing very high music output peaks without distorting.
Some view I-Tech's unconventional power matrix to indicate that I-Tech is not "good" or is "unstable" when driving low impedance loads. Nothing could be further from the truth. A fundamental advantage of Class-I is that it cares little about the load impedance. Pile on the speakers. I-Tech isn't afraid.