If your playing on Elite you dont have time to stand around figuring out which NPCs are doing what. You have to know that before going into the fight and target the healer first. In this case actual gameplay > immersion.
Giving away who the healer may be gives the game away on the other hand. Better to find it out yourself in my opinion, using the obvious clues of "Look that NPC is visible healing his allies" for one thing. Even on Elite.