They're right. If you're a Melee DPS, you shouldn't be trying to pull multiple enemies if you can help it. It'd be one thing if you were a BLM since you could cast Sleep on a group that's vulnerable and then single target, or a Ranged that can use Foot Graze to pin one in place while you deal with another. But Melee DPS only have Arm's Length, which can cause Slow, Feint, which will reduce damage for a few seconds, as cooldowns. If you have to pull more than one, the best you can do is pop those, Low Kick the one that hits hardest, and then proceed to pop Bloodbath and try to kill them all as fast as possible.
If you have your Chocobo, they can Tank for you. In a worst case scenario, let the Chocobo distract all the enemies and run away.