Lately, a lot of people running tank specs are focusing on survivability over all else — i.e., “turtling.”. The thought isn’t wrong per se, but it doesn’t help your raid as much as you think.
An example of a turtle build is running 2 stamina trinkets + the most defensive legendaries and defensive talents when available, giving a tank more room for error and allowing you to live long enough for the DPS to screw up and cause a wipe.
On the other hand, you have a DPS build, which runs 2 stat sticks, the legendaries that provide the most DPS, and offensive talents that do not sacrifice necessary talents.
These builds are both viable and are used in different situations. A ‘turtle’ build is mostly used for progression to stay alive as long as possible and let the DPS/Healers get used to the encounter. As you farm a boss, you should gradually shift towards a DPS build. How quickly somebody shifts to a DPS build depends on how good of a tank they are and the degree of trust they share with their healers.
There are also have the people who believe that a ‘turtle’ is the best build for a tank in every circumstance. These players are proud when they kill with grey parses, because they believe they are the reason the DPS/Healers didn’t die. This is fundamentally wrong, as you can’t help DPS with their mechanics. If they make a mistake with their mechanics, they will die no matter how much you turtle.
To be a tank, you just need to do your mechanics and not die. But if you want to be a decent tank who brings more to the raid than the average player, you want to also bring DPS to the table. Let’s take a hypothetical example:
A tank is applying to a new guild because he wants to get further into the raid than the first 3 bosses. He applies to a guild that is 4 bosses into the raid already, but another tank applied to the same guild. In terms of survivability they perform around the same, but one does 400k more DPS than the other. Of course the tank with the highest DPS would be accepted into the raid team because he brings more to the table than the other.
Survivability is built into the kit of all tanks: it’s called Active Mitigation. For a Brewmaster, this is achieved by using Ironskin Brew and Purifying Brew. If you know how to abuse these tools, you can easily get away with running full DPS setups on most bosses (edge cases might still force you to go turtle). So other than giving your DPS more time to screw up their mechanics and causing you to take unneeded damage, there really is no reason to go turtle on most of the fights.
If i compare my logs against the logs of a turtle, I will almost always have less EHRPS. This is because DPS-focused tanks use their class to the fullest by not relying on the extra cushion that turtling gives you. They use all their resources available instead of wasting them.
Another argument I occasionally hear is: “if I go turtle, we can drop a healer for a DPS”. This doesn’t mean that turtling is a good idea. This means that you as a tank are not using your class properly and are taking unnecessary damage. A Raid Leader will never drop a healer based on tank damage. A Tank is supposed to make sure they are healable for the healers. If you stand in fire, you won’t get an extra healer just so you can stand in the fire.
 external healing required per second