Is leveling broken in this game?

[Godsfaith]

Keep your weapon up to date with your level for max DPS no matter the job. If you out paced the MSQ I would focus on that, because MSQ gives the most exp. Someone advised to level another job. I leveled my tank to the exact level of my MSQ once my healing maxed and was 20 levels above my MSQ point.

Once you have no more MSQ quest to do, you will see how your leveling process will change significantly.

Also with 1 class at max level you get an armory bonus, there is helm, earring and necklace that increase exp as well.

[Iscah]

Also with 1 class at max level you get an armory bonus

You don't need a class at max level. There's old information (still in the game) that there was a sliding scale of how much bonus you got depending on the difference between your current class and highest one, but even that has changed.

It's just a fixed bonus for any class that is not your current highest-leveled class. 100% for Lv1-70 and 50% for Lv71-80 if I remember correctly.