In fact, trhere are 2 thought-schools regarding fighting :
- Strongest first, then weakest
- Weakest first, then strongest
I have never heard about 'two schools of fighting' I would suggest you are mistaking tanking versus dps. It makes sense to have tank make sure that the strong target is focused on them, while dps kill the weak targets. Perhaps you need to look at this from healers point of view. What would you like to happen if it was you who had to heal the group through an encounter.