1) Battle royales suck. The entire genre. I grew up on arena shooters - your Quakes, your Unreal Tournaments, and so on. Getting booted all the way back out to the lobby to go through deployment again because of a single death isn't fun. It's making me replay the most boring aspect of the game. Call me when there's a popular one of these which has multiple lives or some other mechanic that ensures a single mistake doesn't result in ~5 minutes of being unable to play the game. I don't have the time or the patience for this.
2) Fortnite's success killed two games I was really interested in - Paragon, a gorgeous third person MOBA, and a reboot of Unreal Tournament.
Those first two are very concrete and have nothing to do with tribalism. The last one is a bit murkier:
2.5) Fortnite seems to be aggressively marketed towards children, which means its players are probably disproportionately children. Minecraft had this problem too, but it had a single player mode and private servers which allowed you to sidestep it.
That one probably carries the whiff of "kids these days", but when you consider that the game is going to be designed to cater to the average player...