The reason it's more pervasive here, is because tank/healer specs in World of Warcraft (I'm going to name it, just like I'd name "He-Who-Must-Not-Be-Named" as "Lord Voldermort") do pitiful damage. At least, pitiful compared to what tanks and healers can push out in this game. We're talking 60-70%+ of a DPS's damage that can be done by healers and tanks. Trust me, that really is nothing to scoff at, and makes a MUCH bigger difference compared to WoW tank/healer specs (I used to play WoW btw, did some raiding back in Cata too, as a Resto Druid). Now, I'm not the sort of person to care over numbers too much (even in Extreme primals, I'll probably care more in Savage though), but I can understand why people do see them as the holy grail in tanks/healers here. Our tanks/healers are much more DPS capable compared to T/H of other games.
And, to counter the point about ICC10/25. Chances are (although I could be wrong here), you were in a static. Generally speaking, statics here work much the same way as statics do in WoW. Everyone is already on the same page, and knows it's in their best interests to take what's best for the team. But when you head outside of statics, you're likely going to encounter much more conflicting opinions. Why? Because you're not in a group of people who know and understand each other. Not everyone is going to be on the same page. That's where the conflict comes from.