Originally Posted by
Kralljin
Yet this was primarily about support buffs / debuffs.
Unique utility, primarily stuff like Windfury Totem, Blessings, etc..
In Vanilla / TBC, every Buff / debuff from a given class / spec was unique, if you didn't have a Shaman, you didn't have WF and your Melee dps heavily suffered.
So they changed a lot of these buffs to be replaceable with each other, so you could bring a Frost DK instead of a Shaman if you wanted to.
That didn't have anything to do with Interrupts or dispels, because these were already shared among a multitiude of classes since Classic.
This entire "Bring the player, not the class" originiated from the extreme ends guilds reached in TBC where one class / spec was so much more valueable than another simply because it brought this one unique tool.
As said, neither interrupts nor dispels were in any fashion unique.
A lack of Interupts was never an issue in PvE, neither were dispels.
Let's not forget, this philosophy was implemented in Wotlk, not Cata, not MoP, this where it had the biggest impact on the game, yet that's the expansion that you hail as so amazing for PvP.