Super Guide, as in the "!" block that pops up in Mario games? Those suck ass. Whether a game is "ruined" is a different and bigger question since you have to look at the game as a whole.
It's where if you start sucking enough an option appears to let the game play itself to get you past the bit you're stuck on.
I'm curious though: what makes "FTL" different when save scumming pretty much destroys the combat system and challenge (if not a number of other things) in a "RPG" - i.e. the "core design".
It's a whole game designed around the gimmick of Iron Man mode. The game has almost nothing to offer if you, not only if you added in quick save, but if you added in any kind of saving at all that didn't result in your save game being wiped. The addition of
quick save itself wouldn't break the game, rather it's the ability to load your save from anywhere that would break it. The intensity of the game comes from the fact that your whole save game is permanently lost if the dice gods fuck you (and they do fuck you, often, resulting in a variable ratio reinforcement scheduling).
This is possible to create in any game, but in games that take longer than like 90 minutes to finish a single successful playthrough, approximately ten people on the whole planet have the patience for it, and for these people we include Ironman Modes in videogames. FTL is built on Ironman, therefore QS/QL make sense to eliminate.
By contrast, Deus Ex does not magically lose its appeal thanks to save/load, or quick save/quick load. Actually, QS/QL come in many types with different implementations, so it's disingenuous to assume that we are only talking about the ability to literally save at any point, even if they are unwinnable, or during combat, or what have you. Saving of all kinds are sometimes disabled if "danger is near". Saving is almost always disabled if you're in the process of inevitably dying. QS is just a convenient form of saving without checkpoints or save points, and not all implementations allow you to save scum during combat.
It is also unfair to focus purely on the negative outcomes of QS, and not on the positive ones. If used properly, QS reduces frustration in difficult encounters by allowing you replay only parts of the fight, instead of the whole thing. It encourages experimentation at all points in a game (Crysis 1 is a game that I believe benefited
massively from Quick Save). It also means you don't have to replay large sections of game if checkpoints were placed improperly, or worse, they
don't even exist.
Now imagine a game where he was forced to live with the consequences. His actions would gain more weight (and likely require more thought) and by extension the NPCs, who are currently nothing more than disposable meatbags that can be put back together on a whim, would too.
This is an argument for taking out quick save in only one type of game, but actually these kinds of things can be encouraged even without eliminating it, by making the consequences of some actions far removed from the action, and also far-reaching. Thus, we can keep cool experimentation ("wow, I'm going to chop that dudes head off to see what happens short term then load to go with the choice I'm actually going to make") The Witcher games were already mentioned herein.
But your hatred of QS seems to be implying that you think the default position should be that they are not included in games, which is the opposite of my thinking, which is that it should always be there, unless the game is
especially harmed by it. Even then, I should say that hybrid solutions ought to be considered before outright removal of saving on the go (i.e. no saves during combat or when enemies are near).