Right, but this is a false charge, because people really do understand that all of the above actions require skill -- or technique if you prefer. What is implicit in their position is that the margin of error for placing the first headshot on someone in a 1v1 DMR duel -- versus landing a Reach-style grenade in their vicinity or, Jesus Christ, firing a Scorpion's cannon in their general direction -- is much finer. When someone says the latter things take "no skill" they are using hyperbole to express "much less precise technique".
And in the context of Heavies, all those sloppy margins lying across one another in a cluttered and at times arbitrary environment where things spawn frequently and sustained resource (i.e., weapons and vehicles) control is mitigated against, the "technique gap" if you like, gives greater expected value to underdogs. Which isn't inherently bad, let's be clear, but causes dismay to those who are typically not underdogs (e.g., oh, I don't know, kylej), because their +EV is being chipped away at.