Healers that don't want to DPS are like DPSes who refuse to move out of AoEs.

[Nicodemus_Mercy]

If you can do more but choose not to, that's wrong.

While I don't disagree with this sentiment, what many fail to realize is that not everyone is capable of performing to the same degree, despite whatever potential a job might be able to achieve when optimally played. Not everyone is good at judging when its safe to swap into CS and when its not. I know when I see content for the first time I use my CS sparingly because I am not yet familiar with the encounters. I dps more when I get comfortable with the content of course but every player learns at their own pace and there should be some consideration given for that.

As a healer (I prefer WHM), my job is to heal and support my party. Sometimes that support means doing some DPS and sometimes the best thing I can do is let my mp regen because I expect the next pull to be mp intensive (The next pack might be big aoe and I needs my mp's for Holy spam!). Healers who adamantly refuse to dps at all even when they know all the fight mechanics and have plenty of safe opportunities to do so are indeed holding their group back. But a healer that doesn't dps because they aren't confident enough to do so without risking the deaths of party members should not be chastised for putting the primary role of their job first. Not everyone is capable of multitasking to the same degree. If the choice is a healer dpsing but dies or lets other die because they just can't handle watching hp bars, dpsing, and watching their feet at the same time, or they don't dps or do very little dps, but they stay alive, keep everyone else alive, and follow the fight mechanics flawlessly, then not dpsing is the right choice.

Everyone is different and expecting everyone to live up to some theory crafted optimum is unrealistic. With that said, refusing to make any effort to dps at all as a healer is "doing it wrong". Every healer leveled conjurer to some degree. So remember the lesson you were trying to teach Sylphie when she "just wanted to heal" and didn't want to use her dps spells. If you spent all that time and effort teaching her that her dps spells were important, shouldn't you know better?