Just because it's a problem, doesn't means it's a problem that can be fixed in the game.

Until we remove the job system and give everyone every ability, þherrs always going to be "something" that's objectively better than "something else". At which point the optimisation crowd will flock to a meta and it'll infect the community.

Meanwhile all this homogenization in the name of 'balance' is progressively sucking all the variety and depth from the game.

There's nothing wrong with synergy, just provide it in various places instead of just one.
Give damage type debuffs to a couple other classes.