Define 'wrong'
As a tank I keep every mob on me no dropped aggro, but I only did 1-2 packs at a time and not wall to wall. Am I wrong for going at a pace I feel comfortable with and know I will get everyone through the content.
As a DPS am I wrong for singling out that Wasp that has a near OHK first before aoeing everything the tank brought together. Does it take a few extra seconds to get through everything yes, but I killed something that could have messed up how the group was rolling.
As a healer I throw out a GCD barrier a bit more often because I want a little more 'cushion' on the tank's health just incase someone misses a wasp sting or similar, my DPS is slightly down but I minimized the chance of a hiccup, lagspike, etc screwing my healing up by being slightly proactive.
They might not be 'optimal' in many people's eyes, but are those playstyles truly 'wrong'...no.