The answer is kinda yea it is, if the tank has a much lower ilvl than the dps that are doing spike dps then it will be harder to do what is considered "good" dps while maintaining control. The reason why SMN and MNK can control it better is simply their DPS is drawn out over a longer period of time whereas BLM DRG and BRD all specialise in instant damage. Healers are a different matter simply because their enmity only ever gets to dangerous levels when they over heal and that's easily avoidable.