Tomorrow you hit a monster 10 times for 100 damage per hits (1000 damage total) with any non enmity generation attack then any DPS/Tank (out of enmity stance) using any non enmity generating attack/or even a SMN/BLM using ruin/fire once come & deal 1001 damage after you, they will get the threat off you due to your raw DPS number being lower than their.
You're tanking on any class (you have 20k HP) (again with no enmity generation bonus applied and you get to hit the monster once for (lets say 2700HP) while he dropped your own HP to 10k, then you turn away. A healer come & spam 10 cure I on you for 400HP each (giving you back 4000HP total), while another one come & give you only one cure I for 4020+ HP, they will rip the threat off that other healer (and you) in one go because their cure raw number was higher than the other healer or even the 2700 raw number you dealt in damage, all of these exemple show you any non enmity generation TP/spell used, they're all just raw numbers sent to the game which establish the treat meter accordingly to the highest values.
Now take a Dungeon pull scenario with a spell like Unleash (which has an enmity generation bonus on top of making raw low damages) and any DPS focus on 1 random target, while enmity is something that decrease overtime, if it wasn't for that enmity bonus applied by Unleash, the DPS would steal aggro off you straigth away because of their higher raw damage value. Same can be said about flash "increase enmity in all target around you" <-- remove that & the blind effect will not sustain any enmity on its own. This is why you have to reapply Flash 2 times on your packs & why you have to rotate your Rage of Halone combo on each targets in sight if the DPS/healers have a weapon iLv similar to/ higher than your weapon iLv, and why tanks can't keep enmity of DPS who outgear them by 25+ iLv, this is also why you have to turn off any regen spell cast on you while you pull because it count as "raw value" toward a group of untouched mobs linking in a pack of 3.
As for something like an enhanced Dark Passenger? They have no enmity modifier either and generate only a little treat based on raw numbers, this skill is purely here to DPS & blind target, unlike Flash which is there to increase overall enmity on all target & blind them.