or your players
I try to avoid “gotcha” DMing. It’s frustrating for players to focus on what feels like an unimportant detail. If the players are wrong about what’s unimportant, then give their characters a wisdom save to notice.
I can easily imagine what a stronger person would be able to lift. But I can’t easily imagine what a wiser person would remember to check.
Yeah, if you were actually in this situation, that isn’t something you’d just forget, unless your intelligence is extremely low (low enough that you probably wouldn’t have the idea to use the rope in the first place). This is bad DMing. They should have said something like: “You’re aware no one is holding the rope. Are you sure?” If that’s actually what they wanted to do, they can do it. If not, they are now aware.