Unless they fix the hard limit that mobs have on the number of effects that can be applied, DoT caster will not be a thing. It is a pretty high limit and it's hard to reach, but there are instances of it still being hit, and if you have a job whose DPS is entirely dependent on DoTs and they can't land them because the limit has been reached, then you have a useless job. This applies mostly to hunt mobs in the overworld, but even TOP I think ran into this problem with a few cases.