Just want to add a little something.
"Competition" between Tank and DPS. Tank maintaining threat without a DPS threat dump when your DPSers unload everything, cooldowns, relics, adrenals, pre-casting at the beginning of the fight. Something Eudorus / Donn (maintank of suckafish until NiM TFB ish before he quit) was mindful to remind us DPS back in the day.
There may be some fights in the future (in the past i think the first phase of 8-man NiM TFB is an example) where target resets happen faster than your DPS will have their threat dump on cooldown. Add an enrage timer and it can be a problem if the tank does not have enough threat.
There are tanks who would rather just yell when they lose aggro, and then there are tanks you grab aggro from today but never tomorrow.