I guess we are unique, in that we yank on the door, both when leaving and arriving to confirm it shut and locked, at home, in a hotel, or a condo. But yes my wife would be freaked out, however she secures the door, including the chain thing, so someone would have to overcome all of that in order to come in. I would say about 10% of the hotel rooms I stay in has a door that doesn't fully shut on its own, I have to help it. No big deal, but I value my security and I confirm its closed and secured. I've yet to see a deadbolt or chain somehow reverse themselves, and drunks and hotels are so frequent I often wonder why bartenders don't cut people off as they can't even remember what floor they are on, let alone room #.
So sounds like a door wasn't confirmed shut and secured, and some horribly drunk person went to bed, so intoxicated that he didn't know anything in the moment. Scary, but not the hotels fault, for lack of effort on the OP.