Imaro
Legend
Mark CMG, no, you're right. In 4e, it is not automatic if the papers light on fire or not. It is up to the DM to adjudicate that.
Pre-4e, all DM's were forced by the mechanics into a single interpretation of how fireball works.
It all comes down to whether you feel the DM should be empowered to make determinations or not. In pre-4e, those determinations were solely the realm of the rules. The DM had no real say in the matter. In 4e, it's up to the DM.
I can't believe that I'm arguing in favor of DM empowerment.![]()
Wait, did 4e invent rule zero or something? Because I remember DM's being empowered in any edition to change what they wanted to. Maybe you should actually READ the books of those editions...

As far as 4e goes it's not about DM empowerment, it's about setting a baseline of expectations for a player and the resource he has payed for and controls. As a player I'm suppose to understand the powers I have through the rules text (especially since flavor is malleable). If the rules text states that it only targets creatures... when I pick this power why should I expect or know that it targets anything outside of that? And again the passage you refer to in the DMG is about a PC specifically targeting an object not about whether a fireball can accidentally ignite things or burn things.
From a player perspective this changes the dynamics, usage, etc. of the power from the rules I have been given for it and actually creates a situation where the effect of my resource is dependant upon the whims of the DM.
From a character standpoint... how do I not know whether this spell burns things other than creatures? I guess I never targeted something in a room full of combustibles before? Or is it that it only has this property or doesn't at the whim of the DM... even though it's a spell my character has studied and cast before?