the battle royalification of games is annoying for sure, but saying it started with fortnite is giving epic games wayyyy too much credit.
fortnite just ripped the entirety of PUBG but with cartoon graphics and worse shooting mechanics. and even PUBG was just taking the lead of minecraft hunger games which was popular YEARS before either PUBG or fortnite were around
except minecraft hunger games was good actually. it was fun and it was just a single game mode that some minecraft servers implemented, not the whole game. there are a ton of server minigames that creative minecraft community members come up with, hunger games just happened to capture everyone's attention the most, and then devs noticed and decided to capitalize with stuff like PUBG
Fortnite pretty much just came at the perfect moment: PUBG was getting popular but was a paid game, while fortnite was free so anyone who wanted to try the genre flocked to it and stayed. I think there were already a bunch of other live service battle royales in production at the time too (like Apex Legends had to have been in production already), epic just lucked out with having a very versatile base game already nearing completion (fortnite was originally a sort of tower-defense game with player building, sort of like Sanctum) that happened to be able to be quickly adapted to the genre. I almost wonder how it went down internally, if it was just some stress test of the netcode that made them realize they could scale it up to a battle royale without any problems or what.
Epic nailed it by the grace of having a failing co-op PVE game already made that wasn't a resource hog.
I cannot stress enough how fucking terribly PUBG ran at the time, considering how fuck-ugly it looked
I'm pretty sure it was still in alpha at the time, and its biggest problems were the dogshit gacha progression that the battle royale kept on. I don't think it was ever actually finished and released properly, just quietly abandoned after the beta of the battle royale took off and epic springboarded off that into having their own storefront.