In many other games, if you win a few rounds (or do well at all), you're quickly pitted against semi-professional players and lose horribly. Semi-professional and professional players simply do not care about their costumes or outfits, and often choose the skin that offers the most visual clarity or blends in the most. You specifically _do not_ want to standout in a -competitive- shooter game.
But, in Fortnight, because only 1 player wins, and because of the chaotic and random nature of the game, and because of the social aspect (playing with a group of friends), I wonder if most kids ever experience a user 10x or 20x or 200x their skill level. It's very likely most players never really improve their skill levels over time.
Watching professional StarCraft or Counter-Strike, graphics and details are turned down to the lowest setting, skins and such are not used, etc etc. If you were never aware of the "ladder of skill" in front of you, or your place on it, it seems more reasonable to focus on cosmetics.
What really interests me is that a few years ago games started actively removing "leaderboards" and "ranking positions" UI pieces - specifically to make new players and poorly skilled players feel more comfortable and happy. There is absolutely a balance here. Recently my 7 year old nephew said a game (RayMan) was boring because "we always win", and I had a great conversation with him about difficultly in life - things that are always easy and always fun are dangerous. Games with intense difficulty are rewarding and memorable - it's about the accomplishment, not the reward. This applies to video games, drugs, relationships, food, and just about everything else in life.
I absolutely am glad his mother doesn't allow FortNight, but allows me to play Chess, Rocket League, and StarCraft with him.