based off the developer update video with drew he mentioned something about server merging rules and it appears they try not to merge you too close to other players. obviously this is conditional. as our players spawn on the ship when we log into the game i think a freshly spawned ship either at an outpost at setting sail or at an island after sinking i dont think that ship is technically considered active until you raise anchor? because i have surfaced at outposts many times when diving to a tall tale to get a better starting location.
so that being said with this whole season being focused in the roar and its a much smaller portion of the map. think of it like why the kraken would always stop spawning with updates and why for the longest time megs werent spawning. those events need a battle area. so the game looks for a radius around your ship that is free of obstructions, rocks, islands, sea forts. and over time they have flooded the ocean with rocks for some reason. either to prevent us from sailing in a straight line while doom scrolling on twitter like we all did in year1. or because they thought it would cool for sneaky pirates to have more stuff to hide behind? pirates life made this much worse as they wanted all outposts to be a launching point for that tall tale. it didnt have to be this way. at the start yea it was the new update. everyone was doing it. but now its so rarely done that choosing monkey island or pirates life from the main menu could put you at a specific outpost and cut down on the number of stone arches. we only had 1 arch at the launch of this game and im fairly certain that got scaled up massively and became the arena tavern? now theres 6 old school arches near each out post for no purpose other than 1 off tall tales. so because there was no clear enough area for pve encounters to spawn they would just get stuck or not spawn. the fix for this was them shrinking the battle area. took years to do though.
so i think right now the devils roar is too congested. they might even have a merge rule of "if 2 ships are in the region dont allow another ship to merge here" as the world has 4 regions this seems like a reasonable restriction to have. until you force the whole community to only play in one region.
so basically the seas feel empty because new ships arent being allowed to spawn at morrows if theres 2 other ships in the roar, ships cant merge out of the roar onto another server if theres already 2 people on every server in the roar as well. so if anything it might merge you off to a new server or would merge you to a server with only 1 other ship in the roar. same problem if there were other ships they would be on the west side of the map then not in the roar so it would feel empty.
just add this to the list of conflicting game design concepts. usually if you are out in the roar hiding from the rest of the server they would merge you off the server because you were alone. they want you to be near other players so the pvpers can come sink you. they prioritize pvp fun over pve fun. but then they have limiters like this so you arent out doing the molten sands fortress for example and all of a sudden 3 ships recently merged into the server in the same reason. good luck selling your loot!