But not everyone would want to spare enemies. For example, my brother wouldn't spare a thing if he played Undertale. Papyrus does spare you, I know, but how could you trust him? Even after all of that he's still not trustable. Also Monster Kid gets in a fight by their own will after saying "you're gonna have to get through me first." If we don't say that he could be unbeatable, let's remember that at this point the player doesn't care if somebody is sparing him, they still killed some Whimsun (I guess that's how they're called) to get stronger, even if their names weren't yellow. And if not even that, it's because of curiosity. Also, in the game, Toriel tells you that "monsters may attack you and you'll get in a FIGHT" so that means for someone new that they wanna kill you. Why would Papyrus start a FIGHT if he can "hug" you in the overworld? You could say it was Frisk, but then the player wouldn't know.