[Endoperez]

Most games will propably see the use of SCs. It is better to ask would the player have won the game without SC or lifedraining. Especially when lifedrain is also a spell (that can be casted from an item!) and in that case the melee-drainers would not see use. With that wording your question and interpretation (sp?) seems to be along the lines of this one, although not as strongly:

Are games won without use of elemental magics?
Are games won without Evocation spells?

If not, evocations, especially elemental ones, are obviously overpowered!