You have to really keep in mind the type of players that go out of their way to use forums. They tend to be endgame oriented tryhard looking for a place to vent.

Outside of high-endgame content there is little expectation for a Healer to dps. I mean if healer is having a really easy time healing its "nice" for them to throw some dps spells. But no normal content outside of raid remotely requires Healer to contribute even a single bit of dps.

Most ranting you see are from bitter endgamers you got pissed off by low-dps healers in endgame so they taking out on people who will never play at that level in the first place.