Ah, if only this were universally true.
I agree that is the way it is supposed to be, but humans inherently have a desire to compare themselves against others. And in an Organized Play environment like Adventure League (or the Pathfinder Society, RPGA, etc.) people have a way of measuring their characters and their decisions up against total strangers, because everything is standardized.
You all have the same character options and stat options, you all play through the same adventures, and you can go to a Convention play with a total stranger who's character plays the same role as yours in the party. Or you can read about their characters or their build online. Comparisons are inevitable, even if they shouldn't mean anything. The goal is to have fun, but feeling that your character doesn't measure up can diminish your sense of fun, if you are at all competitive.