Something people seem to forget whenever "open world content" gets brought up is hunts. People hate them. They aren't fates, they arent instanced, yet the community largely despises them. Why? Because you have to be there when the hunt is active to get credit.

Now lets take an open world dungeon. It has boss inside. Someone kills it. Now you can't until it respawns. Now there is a large group there. Ok, now you have the problem with hunts, either people pull whenever it spawns and a large group miss out on loot, and you have people whining about early pulling and all that garbage again, or you reduce it to being claimable, where only 1 party gets loot. then you have bots and trolls lining up to control the spawns.

Fates are a way to make open world content work. This is why they are so heavily used. You get rid of the "fate" and its just a world mob with a despawn timer. Think of them that way instead, if the word "fate" bothers you so much.