You're only thinking of disabilities as physical handicaps, and you're only thinking of difficulty as a desirable gameplay element.

A person with a cognitive disorder may not be able to enjoy Dark Souls as is, but if you give them the option to make the game slower, then they can experience struggling against Sif.

It's honestly gross as fuck seeing everyone be like "Nah the game has to be experienced in one specific way which happens to be the way I did it, and if people can't do that then too bad. Why would it matter TO YOU if people alter THEIR experience?