Originally Posted by
Kalise
Ehh... It's not always the case.
Since, there have been times in MMO's when the top tier tanks were the ones that were most self sufficient, which meant that the healers could spend more time DPSing, or they could replace a healer altogether with another DPS, replace the off-tank with another DPS (Because said self sufficient Tank could cheese through boss mechanics #JustDKThings) or otherwise adjust to push out more DPS than if they just took the Tank(s) that would provide the most personal damage.
Though this was alongside more options for healers, such as builds that would work via dealing damage to things acting like a 0.5 healer 0.5 DPS. Or other mechanics such as WoW's Shadowpriest giving an aura that gave lifesteal to everyone so basically everyone had a mini-Bloodbath active at all times. I suppose the FFXIV comparison would be running a RDM over a healer to primarily damage but also spot heal with Vercure and help out against deaths with Verraise. (If not also including any changes to classes, such as if Mantra was turned into a mini-Bloodbath effect for the team)
Heck, I remember some boss encounters in WoW where you just didn't need a healer at all because a Death Knight could cheese the bosses mechanics so hard that damage wasn't taken due to various things like AMS removing the stacking debuffs as well as percent health healing with a exponentially increasing health pool.