Dear Monk,

Sometimes bosses will do a complete 180 from the tank in order to execute a mechanic, like the Gyascutus & Nidhogg fights from the Aery. If you actually wait instead of trying to reposition yourself for a boss that's literally only going to be turned around for 5 seconds, then you can actually keep up your dps instead of trying to go around the massive body that is Nidhogg only to have him swivel another 180 back to me once you get there.

There also exist situations like with the Rangda fight in the Aery where the tank has to move to a statue if they get marked or needlessly suffer over 6k damage. If there's a Bard or Machinist in the group, fine, but otherwise it burns a serious hole in the healer's mana or expends a long cd ability like Benediction to fix that kind of damage.

Even with normal mobs, there are times where there are 4+ enemies with area of effects, and all of them are pointed at the tank, but they aren't necessarily all going to begin those aoes at the same time, so when the tank moves out of the way of one aoe, the other 3 will shift to the new position. I know that I personally am very conscious of the enemy positioning and always try to make it easier when there's a Monk in the group, but there are a lot of situations where it's just completely out of the tank's hands.