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

[Belhi]

Also, a healer dpsing isn't taking your job, it's helping you with it since they actually can do both. If a BLM/SMN heal was as strong as a healer class spell, you could see them supporting the healers if needed, but the 500 heal vs 5k heal is nowhere nearly helpful at all. On the other hand, a healer's DPS is really strong and high enough to contribute to damage. Not nuke dps, but constant dps.

You know this argument would actually hold a little more weight with me if I ever saw dps using their Mitigation support skills. Both SMN and BLM have Eye for an Eye and Virus and BLM as their magic damage mitigation skill but the amount of dps I actually see ever using it is almost non existent. I will usually auto commend any dps that does. Likewise, you only occasionally see someone bother to use Mantra during high raid damage moments.

All these skills are off GCD and for the most part would probably allow Healers more time to dps but almost no one bothers to use them. Group contribution is a two way street.