Okay, I'm a cash-gamer, and yes the gap concept applies to those. Tournament poker is not this thing unto itself. It's poker, and winning tournaments comes from playing solid, winning poker, not tournament poker.
The gap concept is extremely important in cash play. For example if UTG opens with a PFR%= 3% and you look down at AQs, well then you better be tossing that since your equity is somewhere in the 35% range.
But then if villian's utg opening range is 10%, now you have a profitable hand, with a little over 50% equity.
The same principles hold true, if you're going to play a hand, you want your hand to be better than the range your opponnent is willing to play from his position.
This "rule" fluctates as stack sizes change, becoming more important as stacks shrink, and less important as they grow. Once stacks get above ~ 150bb's then speculative hands start to gain a lot of value, and "big" hands like AA, KK, AK, become lesser holdings. This normalization of preflop holdings is a function of betting occurring over several rounds rather than getting all the money in preflop and on the flop. Additionally, the importance of the gap concept is inversely proportional to stack sizes. When stacks are small, < 40bb's, the gap concept is of extreme importance, as you have little time to catch up before all the chips are in. Hands that are best preflop and on the flop are the big winners. However once the stacks get deeper, suited connectors and small pp's have enough wiggle room to take some flops, and win a monster pot here or there against those AA's, which allows them to played profitably against them, which in turn lends itself to caring less about having the best hand preflop, and more about having the best hand when all the chips get in the center of the table.