I mainly played tank and very rarely had a problem with wiping, i always watch after the party to see if someone is behind and if that someone is the healer. I stop pulling if mages or healer are low on mana (much to the displeasure of dps spazzing out nearby) and let them drink, etc just common decency.
But now i started playing a disc priest and all hell breaks loose after 5 or 10 min. I'm level 66 and feel like i'm losing hair. Let me explain.
RDF is filled with dps heroes queued as tank that have 0 patience. They're all about SPEED SPEED SPEED, FAST FAST FAST dungeon, rushing through all the mobs thinking they can't die because of the heirlooms, well... it was me Barry, i was keeping you alive with shield and heals. And the party members getting hurt by you losing agro, it was also me. Ever wondered why everybody was at full health after you pulled 3 extra packs that downed you to 50% in 3 seconds? Ever wondered why your healer's mana bar was not blue after such encounter? Ever wondered what the blue text in chat saying "mana" means? Probably a bug or some anime waifu, you're gonna find out in the next pull.
My experience as a healer is pretty bad, having to watch the "tank" rush ahead while my mana is 30%, then run around him because im oom and i'm also being chased by mobs because he lost agro.
But i also have to admit that it's funny, because i'm the first one to know ahead of time if we wipe and when i read the chat and see "what are you guys doing?" and my favorite one "healer?", i can't help but chuckle.