I’m perfectly fine with certain fleet tasks being able to invalidate certain tasks, but only if it is either a monotonous task, or the fleet task generates less of whatever it generates compared to a player who dedicates the same time to get the same resources.
Since if someone wants to just do treasure charts, then go ahead! Your fleet can get fish scales so that you can brew luck potions, you want to sink ships? We’ll go ahead and have your fleet generate drachma for you so that you can repair your boat, you want to just explore the world and visit diving structures? Well let your fleet harvest some reagents so that you can brew water breathing potions!