The main drawbacks of realtime combat
Atleast half the combat rules of the PnP game goes out the window because it cant be translated to realtime
The tactical aspect of the combat disapears almost completely and is replaced by twitch elements. NOT necessarily FPS combat but more like "attack, attack, press health potion shortcut, attack, press mana potion shortcut, press special attack button, press magical wand shortcut button"
The main villain in the death of turn-based combat is as usually, Diablo.