The tank is going to start in tank stance in most casual content, and build enmity enough before switching to DPS because they aren't going to have a NIN to dump aggro or another tank to shirk aggro on them in much content. Red mages opener isn't THAT much DPS, you have all of two OGCD that do sizable damage and 4 OGCD total. Then its just building damage through GCD. The problem is you don't stay in tank stance long at all and rely on more or less cheap tactics to overcome the lack of enmity that don't happen in much of the game, and you use comps that focus on stacking buffs that don't always happen in many party setups.

raiders really cheese a lot of things and think its skill when its not. If the boss ever decided to reflect debuffs, you'd all have no idea what to do.