Are healers lazy or do some really live by "I only heal"?

[Sareal]

If a healer doesn't dps. ;x I just get out of my tanking stance and DPS in full STR gear after setting hate. Might as well increase your damage a bit if their going to contribute 0.

While it is common to find unskilled tanks, it is not specific to the point of generalizing that "DPS stance tank = Dead tank", it's more in the line of "Bad tank using DPS stance will cause these kinds of situations to happen", in which case, this is specific in the sense that you will find noobs in all and every roles. I just don't see how we should look at that specific situation simply because there are less skilled people than others.