The argument is that because hybrids have the ability to heal or tank, in addition to dps, that they shouldn't be able to do as much damage as those who are pure. Pure dps refers to Hunters, Warlocks, Mages, and Rogues. Hybrids refer too... well everyone else.
There are 2 points that I want to present.
- Pure DPS are less limited by threat due to having Threat Dumps.
- Hybrids CANNOT dps while healing.
Threat Dumps refer to Feign Death(hunters), Soul Shatter (warlocks), Invisibility (mages), and Vanish (rogue). Pure classes have the ability that, if they pull threat, they can get rid of that extra threat and not get eaten by the boss. Now all dps (except hunters) have threat reduction talents so that they can deal more damage without pulling aggro. The difference though is that when a hybrid pulls aggro... they have no option but to stand there and get squished.
Priests come closest to having a threat dump in fade... but that threat gets returned to the priest once fade wears off. Additionally that talent is more to compensate for healing priests being extra squishy compared to other healers.
I'm usually second in dps in our 10 mans and top 5 in 25 mans on my shaman. Yay for me right? Well on fights like Hodir I'm constantly riding the threat line of our tanks. This means that if I'm not careful I will pull aggro and die. This means sometimes I actually have to stop dpsing to let the tank build up. The pure dps... just reaches the threat cap and pops their respective abilities and go right back at it.
What happens in the above scenario when the tank dies? Or in our case gets flash frozen and bubbles /glare. Well MR. Hodir comes over and smacks me with his big giant mace and then turns around to go after the rogue. The rogue says LOLVANISH and Hodir goes to find someone else.
For the record... being able to heal isn't going to save you from a boss one shot... nor is throwing on a shield or switching to bear form. If you pull aggro as a Hybrid you are left to the mercy of the tanks taunts (though I did survive a melee hit from Archavon once).
The second point is really the one I've been thinking of a lot lately. You see I've talked about it before, and while yes being able to spot heal can save an encounter... so can some extra dps. Blizzard says that because we have the ability to heal, that we should be lower then pure classes in terms of damage. Why? My role in a group is DPS the fact that I can heal alone IS a dps decrease.
When I have to stop and heal myself, or a tank, or that dps who wouldn't get out of the fire, I'm losing dps. The time it takes for me to cast a lesser healing wave is the same amount of time that I could have been casting a lightning bolt. The last time I can ever remember going an entire fight without casting a single heal is Patchwerk. Every other fight I've done there are times where I have had to stop and heal "someone". That ability to heal costs me damage.
Don't get me wrong... I love playing a hybrid... but there are times I wish I could just straight dps through a fight... just to see what my actual potential is. I may never catch the rogue in our group in damage... but I hope that it isn't because of some "5%" difference inherently between us. There have been a number of times where I have been low on damage... only to flip to the heal meters to see the missing dps in hps.
I'm very competitive... to the point where I want to start bringing my hunter into raids just so I can focus on one job... Killing stuff.