You keep making this point, and you keep being wrong.
Are you saying the 50k dps I do on the first boss in hour of twilight means I'm going ot do 50k on every fight as a dps?
Or when I do 45k hps on ultrax lfr, that I will match those numbers on everything?
It's not wrong if you think about it, try to consider all the variables and view the outcome from a broader perspective, and not just the recount "DPS" number at the end of the fight.
Perhaps a better way to phrase it, would be "AP and SP for Healers and DPS scale with gear"
Of course there are going to be raid buffs that have a predictable effect, an extra 10% attack power and 5% primary stat is the same as gaining that through better gear. All that changes is the source. Trinket Procs, Popping Cooldowns, all come into play.
And OF COURSE the DPS will vary per fight, due to fight mechanics. "Hide during Black Blood on Morchok" versus "BURST the tendon on spine!" The fact that you keep going back to this leads me to believe you're looking at this too narrowly.
But despite the variable mechanics, their AP/SP values remain fairly static. Any trinkets, procs, and mechanic phases are variables that will modify their stable base AP/SP.Tanks do not have a stable AP/SP
It's another variable and can be viewed as a fight mechanic, sure, but it's greatly different in the way the rest of the fight mechanic variables function. Rather than modify an existing stable AP/SP as a cooldown (+20% DPS during wingz!) or as a fight mechanic (x2 DPS during Hagaras stunned phase) this alters the very base AP/SP that everything else is based upon.
Previously with the Cap, you could assume max vengeance pretty much 100% of the time, which would scale with Health pool IE gear and buffs, and result in a stable AP/SP value, with the occasional oddity. The oddities were too few and far between to really be problematic.Look at it this way
DPS Role: 10,000 AP, +10% buffs, +25% cooldowns, +/- x% fight mechanics
Healer Role: 10,000 SP, +10% buffs, +25% cooldowns, +/- x% fight mechanics
Tank Role: Extremely variable Vengeance based AP/SP, +10% buffs, +25% cooldowns, +/- x% fight mechanics