I’ve played the game at a relatively decent level, and the general idea is “defaults” tend to be easier opponents. Of course, most people and specifically kids don’t want to be looked down upon, which leads to the phenomenon mentioned in the article.

Fortnite is special in that skins are very prominent from the so called “defaults”, thus someone with skins show that they have clearly invested in the game and therefore (on average) are better players. In other games like Apex Legends (another Battle Royals), the skins aren’t as obvious or are much subtler recolors and slight changes from the base model.