We've been conditioned to hoard stuff.
"Hi, welcome to the midgame checkpoint. To continue, please produce 25 potions that require four different useless items."
"Oh ho, this enemy is impervious to your broadsword. But if you have that one dagger the orphan boy dropped 26 playing hours ago, then you can throw it in his eye and obtain the Orphan's Treasure. This unique item will grant a buff that increases gainaxing."
"Yes, you're low on health, but you can eat 25 cheese wheels. Save those hundred full life potions for when you really need th-Oh that was the last boss. Good job, you win, and the potions mean nothing."
Ok, that last one is a reason not to hoard, but it stems from a thousand boss battles where you didn't have any healing items.