Is hurting enemies and destroying traps in a house by setting it on fire from the outside so different than disarming traps and killing monsters that are restrained by Hold Monster? It's a different method. It could harm innocents inside or destroy items or clues, but using a fireball in combat often has collateral damage. Is burning a house different than shooting a fireball into a cave?
If creatures inside the house aren't killed, they will likely take damage. They might even flee the house to keep from taking more damage in which case the PCs could have readied action to attack them.
Burning down a house is not the usual method of tackling the problem; I'm not sure how you could say its not more inventive than the normal way of going room by room and fighting what's there. I don't see how a sandbox campaign would automatically consider burning down a house a failure.
I'm trying to find where the game defines the goals of play you list: the goals have to include bold adventurers? The adventurers have to have a good time?
From RAW, it seems like gaining levels is the mechanic for goals which can either be gained by experience points from overcoming challenges (most often combat), milestones, session-based advancement, or story-based for accomplishing campaign goals.
If creatures inside the house aren't killed, they will likely take damage. They might even flee the house to keep from taking more damage in which case the PCs could have readied action to attack them.
Burning down a house is not the usual method of tackling the problem; I'm not sure how you could say its not more inventive than the normal way of going room by room and fighting what's there. I don't see how a sandbox campaign would automatically consider burning down a house a failure.
The thing with burning down the house is that as with any particular course of action the players consider, they are well-served to pass it through the filter of the goals of play. The game defines those goals as the DM and the players creating an exciting, memorable story of bold adventurers who confront deadly perils and having a good time doing it.
So the question the players could stand to ask themselves in my view - separate and apart from whether the DM will grant them XP or make gathering the treasure time-consuming or whether there will be unforeseen consequences - is whether burning down the house is going to achieve the goals of play. It might. But then again it might not. To me, it's worth thinking about before proceeding.
I'm trying to find where the game defines the goals of play you list: the goals have to include bold adventurers? The adventurers have to have a good time?
From RAW, it seems like gaining levels is the mechanic for goals which can either be gained by experience points from overcoming challenges (most often combat), milestones, session-based advancement, or story-based for accomplishing campaign goals.