Not always true. You have to pay attention to what markers require these days, some are requiring/recommending the use of LP or HP for one reason or another. The 09 Impulse recommends HP, the BL victory recommends LP so not to push the asa o-ring out of place. Also spyders and tippmanns require HP output, they won't work on LP.
With companies making user serviceable regs and able to swap pressure outputs it's becoming kind of a thing of the past to buy one tank reg and being stuck with it and having to make sure your marker purchases revolve around that so that they work properly.