Some sort of levelling system is required because the game needs to sell you the fantasy that your character is becoming more experienced and a better warrior, and honestly it's not hard to just give every job one or two new abilities or passives every 2 years. WoW specializations are orders of magnitude more complicated than any FF14 job, and yet Blizzard continues to manage add several new abilities and talents for all 36 of them every 2 years, and that's on top of new trinkets. There is no reason why FF14 can't do the same for its jobs every 2 years. I do not find getting gear with higher arbitrary numbers on it to be more immersive than my character simply becoming better and learning new techniques.