Because our rotation is rage, proc and CD dependant and we have the initial set-up that many other classes dont require.
Take a standard 2H rotation in the current phase:
Rend → Heroic Strike Queue → Blood Thirst → Overpower → Slam → Quick Strike → Hamstring
But it’s not as simple as pressing buttons in that order:
Open with any strength or attack power buffs (e.g. Diamond Flask) to snapshot Rend.
Heroic Strike should only queues above 30 rage or you risk burning rage and having down time.
Overpower (with improve OP talent) has higher prio than Slam, unless you have Recklessness is up, then Slam > OP, unless rend is close to expiring, then OP > Slam (with Draconic 2-set), if oyu let Rend drop off, you lose the Attack Power snap shot from your opening CDs.
Bloodthirst in CD, unless you are low on rage, in cases where you are less than 30 rage, you should instead focus on building rage quickly with Quick Strike and Hamstring for Wild Strike proc finish, then Bloodthirst once you are back up in rage.
Hamstring if you are under 10 rage for wild strike proc for hopefully quick rage gen.
So you are constantly tracking Rage and procs to alter your rotation and making sure you account for how your abilities prio change.
There can easily be a 2k dps difference between a warrior handling this perfectly and a warrior fumbling or burning rage and having down time etc.
Then you have the set-up, simply using macros correctly to handle swing timers is like 200-400dps difference.
It’s simple enough, but lots of warriors don’t macro all their abilities, or macros them wrong. All you have to do at a minimum is add /startattack to your abilities but some abilities you put it before the ability cast, some you put it after. This is because some abilities’ cancel your attack swing so you can have wasted swing time leading to less auto attacks → less rage. Some abilities can also use /stopattack as well, so lots of macro work to do (Yeah, you can find most of this online / on discord, but you would be surprised the number of warriors not using macros at all).
If you are Duel Wielding, you also need to be maintaining you weapon swing desync to improve rage gain consistency, you can use desync macros to set it up, but then you need to keep an eye on swing timers as you use abilities to make sure you don’t sync your weapon attacks.
There was even more to do last phase with constantly stance dancing and managing rage dumping.
You also have to at least understand some little bits about how abilities work. The most simple example is seeing warriors in AQ40 gear using Execute. If you have over 2k Attack Power, Bloodthirst and Quick Strike are almost always better than Execute (the more attack power over 2K , the better they scale). But you will still see warriors with almost 3K attack power using execute because it’s the “execute phase”.
When you see a warrior getting 100 parses, they not only have everything external they need (World buffs, Improved Expose Armor, Wild Strikes etc), but they are also doing all this other stuff to do that higher level of dps.
Lots of players just want to put their abilities on their bar and press them. You can do this with a warrior but you won’t compete on DPS with other warriors.
Not saying other classes don’t have their own stuff like this to do, I know Seal Twisting paladins have to be pretty damn precise with timing abilities and using macros to control weapon swings as well!
But there is definitely a big difference between warriors dps even in BiS gear compared to someone doing all of this vs someone doing none of it.