True but the bottom line is no matter if the t-stat is sending out 100 watts or 1000 watts or 10 watts, it is still keeping that spot at the set temp. I see the power feature being used in combination with the basking light feature so you can adjust the wattage to the heat bulb so it still will give off enough light for basking reptiles as well keeping the heat constant. For flexwatt or a RHP, it doesn't matter if it throttles the voltage down as it is still keeping the temp at the set point.
An example would be say you need your basking light to keep 90F. Well once it hits 90F, it will throttle down the voltage which will dim the light to almost not being on. Then when it cools down it will kick the light on. It would be like a strobe light for your lizard. Being able to throttle the power down to say 40% or whatever would just act like a lamp dimmer but with a t-stat function built into it too.