Marking is not a useless thing. Reducing the damage generated by multiple mobs by eliminating them in order you enable:
1. the healer to recover MP more quickly.
2. allow the healer to participate offensively.
3. for WARs, they can save more TP for dealing damage instead of spamming OP.
4. both tank classes will spend more time doing damage and less time using their aoe aggro generators.
Im not saying it's the tanks responsibilty to mark, or that he doesn't need to hold aggro regardless of what's being attacked. But your just plain wrong about marking for priority. It's absolutely useful.
