NGL, this is a bigger issue than people calling the "wrong" targets. 5 people focusing on the wrong target is much better than 2 people focusing on one target, 2 on the one THEY think is the best to focus on (and don't call it out), and 1 on yet another.
Also, it's dependent on range and positioning. If the person they were targeting leaves the crystal and starts running, it's probably best to swap to someone else at the crystal (unless the person running can be finished without too much trouble.
