I think my favorite of all time was Halo on PC.
There was a tool that could freeze time, and you could shoot, and throw grenades, and whatnot, and all the projectiles would hang in the air, and you could just… RUIN the game in extremely fun ways.
I think the issue comes from when you’re ruining an experience. (Hang with me there, I’m all for a super easy mode in Dark Souls.) In multiplayer, this is often everybody’s experience. It’s not actually interesting or fun to win by cheating? If you’re in the right mindset, it can feed the ‘I’m winning!’ rush, but the second you reflect on it, it’s so empty. It also, obviously, ruins the experience of the people you’re playing against. (Usually. A couple other people I’ve met do enjoy playing against cheaters in some situations as an absurd sort of training? (So I know I’m not completely alone.))
In single player games, I think it can add a lot to an experience. It can morph them into something different/new.
I’d played Halo hundreds if not thousands of hours when I finally played it on PC. A time controlling Master Chief, with infinite grenades, sending vehicles into orbit with 100 rockets and grenades, was new. Freezing time to save a marine wasn’t something I could do before. It added a TON to an experience I’d already had.
In Celeste, I was struggling with some of the early levels. I went into the options and enabled, what was functionally cheats. Slowed the game to 50%, gave myself infinite jumps, and absolutely crushed the next level with absolutely no problems. Which felt bad. It wasn’t interesting. I could play through for the story, sure, but I could immediately tell that I’d enjoy it more with maybe one extra jump, or 90% speed, or normally. Luckily, it’s a single player game. It wasn’t a round I can’t repeat. So, I turned off my super powers, and played through the level again. I struggled, but improved. The whole message of the game felt more intimate as someone new to platforming. Try. Get better. You can do it. Don’t give up.
It kinda comes back to harm, in my mind. If you can’t finish a game without cheating, that’s harmful, and it’s better to cheat. If you ruin your experience by cheating, that’s also harmful, but not to anybody else. If you ruin someone else’s experience by cheating, it’s probably not a single player game.
(So give Dark Souls an easy mode, where enemies do less damage, health regenerates out of combat, and estus refills are in more places. Those games are super cool for so many reasons beyond “it’s hard and my ego!”)