I'm curious about the details of those outcomes. What kind of guitar, and how old were they? What kind of neck and fretboard? How long were they hanging for that type of damage to occur? Direct sunlight? Surely you have pics. That would serve as a good deterrent for myself and perhaps others.
I'm in Michigan. Humid summers, extremely cold and dry winters.
The older the guitar, I've found the fewer problems if it's left out of the case. F'rinstance my '65 SG Special was out for years, because by the time I did that it was over 20 years old and the wood was well-settled.
I've always had a whole-house humidifier, but in winter that maybe gets me to 25-30% RH. Not enough. The RH of the Sahara Desert is often in that range!
So a one year old Taylor W-14 I usually left out in my studio had the finish crack off the entire perimeter of the top due to wood shrinkage one winter. And I mean, a100% gap between the top and the edge binding. I had the back of a Martin crack. The fingerboards shrunk on a couple of Andersons (I mean, the fret ends were so far out they were unplayable), but that was fixed at the luthier's shop. I've had slightly poky fret ends on a PRS, though far less than on the Andersons, and the guitars were playable. Fenders have had problems as bad as the Andersons if left out, including some unexplainable neck warpage. I had the finish crack and literally flake off a new Rickenbacker Tom Petty model in the 90s. All of my guitars that were kept out needed quarterly neck adjustments. Then I read something Bob Taylor wrote about keeping the guitars cased and properly humidified, and I figured since I'm really not into the constant neck adjustments and other issues, I'd try that for a few months.
So about 10-12 years ago, I started keeping them cased, and using a room humidifier to augment my whole-house system. Gosh did that solve problems!
Since then, I've NEVER had a problem, and most importantly (just in terms of convenience because Jack Gretz sets up my guitars and he's far from me), none of my guitars has needed neck adjustments. None has had finish problems. None has had poky fret ends. No finish fading. And I've had lots o' guitars here.
So, for those who aren't into keeping them cased, no worries, do what you do and enjoy them! Whatever works for you is great. Not saying anyone else needs a deterrent, I'm just into having my guitars stay really, really nice.
I've decided that I really like what happens when I keep the guitars cased, and in a humidified room in winter. I do think it's the best way to care for the guitars, and I'm all about maintaining the guitars as best I can. I don't consider them easily replaceable or inexpensive! Wood seems to age best in a constant humidity environment.
What Taylor says is that it's not just the humidity issue; evidently the cases also buffer the temperature fluctuations that take place during a 24 hour period. So the wood and finish are expanding and contracting more slowly. This seems to also be a good thing, though I have nothing but anecdotal evidence of this via my own instruments.
I can say that another benefit of casing them is that they don't get dusty, therefore the pots and switches work without being scratchy and with fewer repairs. Remember that kept out in a house where cooking takes place, the circulation of air via doorways and cold air returns will also put cooking greases into the environment, even with kitchen fans, and this makes the dust kind of sticky, and of course the combination of goo and dust also affects the functioning of the controls. And of course, a cased guitar isn't going to get accidentally dinged, or knocked off its stand by the vacuum cleaner, pets, or little kids. Or dinged by the well meaning guest who takes it off the wall but hits another guitar in the process.
I don't have pics. The bad stuff happened for me in the 90s. Long time ago.