The attitude toward 0 DPS healers didn't really cause this. This is just bad players being bad. Please don't take examples and reasoning to the extreme ends. People that want healers to DPS don't want them doing it to the exclusion of healing. Every person that wants DPS from healers simply ask them to do it in their downtime when nothing needs healing. If a healer, upon hearing they should DPS, starts to DPS to the exclusion of healing, they are bad, the concept itself is fine.