Challenge is relative. Comparing games to books or films is just stupid. The barrier of entry to reading a book is also extremely low, even still books are translated, come in braille, large print and audio formats to decrease that barrier further and provide more manageable and comfortable means for people to experience and to ensure they can at least attempt reading said book in the first place. Even when doing so can sometimes obscure or erase some of the intent of the author and their original work. A person dropping a book because they don't like it or find the language too confusing or uninteresting is entirely different from someone dropping a game because they have hit a wall and after dozens of times cannot perform the task the game requires of them. The former can return and continue whenever they like and can reach the end regardless, the latter cannot continue no matter how much they may want to and might otherwise love and enjoy the game in that very moment.
Understanding a book is an altogether different story. In the cases of people with cognitive impairments, or just those without the knowledge or understanding to fully grasp a works intent and meaning, there are CliffNotes type of summaries available all over that often very pointedly spell out the underlying themes, meanings and interpretations of a written work for people to more easily understand them, whether they even read the original work or not as intended. Plus innumerable unofficial summaries and breakdowns by other individuals and sources like Wikipedia, YouTube and more. Not to mention unless the writer of said work is a complete piece of shit I very much doubt they would object to someone else explaining and breaking down concepts, themes and ideas from their work to someone who for one reason or another could not or did not understand them as long as they didn't butcher it in the attempt.
Challenge is relative. And whether someone can eventually overcome a challenge doesn't mean they'll have the same joy and sense of achievement upon doing so as others might. Robust difficulty options not only help to better ensure that as many people as possible can actually play and complete a game, but allows people to adjust things to experience them at a level of challenge that is enjoyable for them. Disabilities are on a spectrum, no two are exactly alike. Whether that's physical or cognitive. Many people with disabilities are capable of completing many of these games, people love parading around videos like that in these types of threads, but that doesn't mean every single person with a disability finds that enjoyable or something achievable without pain or serious discomfort. Options can change that. Whether it's the ability remap controls, select alternative input types, alter visual aspects or adjust difficulty settings like damage input/output, extended reaction windows, alter game speed, etc, etc, etc can turn what is an achievable but frustrating and painful experience into one that is still challenging, but more manageable and enjoyable.
There is no single solution and even if devs were to try to create an experience for all people, that is impossible. All people are on a spectrum of ability and preferences and it's impossible to create one single experience that is suitable and enjoyable for all of them. Which is why robust options are so critical as it allows the individual to adjust things to both their needs and the most enjoyable experience. No two people are alike. Even if they have the same exact issue preventing them from completing something in a game the solution and option they find more enjoyable may be entirely different. If as a result of their impairment a person cannot react quick enough in a fight to block or parry an attack one person might find it more enjoyable, challenging and rewarding to slow the game down, giving them the ability to react in time to the strikes as intended. While another person with the same issue might instead choose to decrease the damage they receive so while they still struggle to react fast enough to block attacks they are able to survive longer and finish the fight at a normal speed. A developer cannot account for this, only robust options for the player to choose can.
It's unfortunate that we don't have a difficulty setting for empathy, because this shit shouldn't be that hard to understand.
