Remathilis
Legend
Within reason. You could add that the acolyte NPC in the MM can cast True Resurrection at will and it wouldn't change his combat stats one bit, but people would probably still want to know why a character who can cast 9th level spells at will suddenly doesn't have a combat ability above 2nd level spells. I liked having a caster level for NPCs to peg what kinds of effects are reasonable for the npc to have.Whereas I welcome the greater out of combat flexibility this brings NPCs and how much easier it makes it to run the game.
(Extreme example used for hyperbolic effect).