We are seeing that the game is unbalanced in a dangerous way with only one or very few large and powerful factions, joined by players who prefer the easy mode as opposed to a good game experience for everyone who bought the game.
If the imbalance continues to grow, it will soon be necessary to zero the game, because there cannot be combat with a single faction or two allied factions; zeroing the game is not in anyone's interest, on the contrary, every time this has to be done, players will give up because they have to start all over again.
On the other hand, no one buys a game to serve as a punching bag.
My suggestion is very simple, implement a port maintenance fee that grows the more ports a clan / faction has, to the point of being financially unviable.
This will mean that players will have to devise more subtle and complex strategies such as controlling the most profitable geographical passages and routes, instead of pure and simple senseless violence.
I hope my suggestion is useful, as I really liked the game, but the way it is, if nothing changes, surely many people will end up losing interest.