Actually... No, it's not. While there is some (little) conflict over when/whether periods & commas should go inside, all authorities agree that
"question marks and exclamation points follow [i.e. go outside] closing quotation marks unless they belong within the quoted matter." (Chicago Manual)
I reckon we are the only monastery ever to have a dungeon stuffed with 16,000 zombies.
I certainly won't argue regarding Chicago. I only selected that version of the rule because it seemed to be the most succinctly stated of all the versions I found.
But the point is that there is no disagreement, apparently, among all the style guides on this particular point.