I had recently been chastised on more than one occasion by people whom rely on damage meters (usually recount), as their basis for assessing how a raid is going. I been hearing "you're not healing enough" when they put me on raid heals with 1-4 others. This never happens in 5-man heroics, because if I am not doing my job, nothing gets done-- it's usually blatant if a healer or tank can not do what they say they can in that situation.
Had these people had any understanding of how Recount works, or what healing actually means, as opposed to "over healing" and mitigation (which can be determined by a plug-in called Guessed Absorbs), they would know that we cant heal people that are not being damaged, which is the purpose of the Discipline tree. I can add the over-healing and absorbs to get a number that becomes equal or greater healing than the other healers, assuming that I am casting as much.
Today, I go to MMO-Chamption.com, and see a blue post that seems almost as if the developers had been reading my mind:
"One of the designers had an interesting experience. Their first Holy priest had much larger healing (total and effective) on the fight than their second Holy priest, so they asked the second priest to go Shadow. They kept wiping. They then swapped them, and made the star Holy priest go Shadow. The second Holy priest's healing was much lower, but they won on the first try. The second priest just had better timing and cast the right spell at the right moment, even though his total and effective healing was lower overall. The moral of the story is meters are very useful, but like any tool, their ability to measure what happens in reality has limitations. In my experience, players put too much emphasis on them, especially for healing." Source.
Blizzard knows for a fact that healing is generally subjective, and should not be judged by meters, because there is a lot happening other than healing. This example was not between two kinds of healers, but I think it illustrates how completely inane healing meters can be, especially to people who are used to relying on it.