Yep.
The physical barriers should be removed, not the gameplay barriers.
This line of thinking is misguided. It's absolutely awesome that a quadriplegic person was able to feat Sekiro, but that was a personal independent achievement absolutely not reflective of the norm. In fact that's what makes that achievement so incredible. Much like that dude who marathoned all the Souls games and Bloodborne without getting hit once, awesome, but irrelevant when discussing thinks like difficulty.
Difficulty is often not balanced for the extreme, but instead the average, and when discussing accessibility one always assumes that it must refer to the disabled, but it would be silly to assume that all able bodied people are of equal capabilities. Accessibility means for everyone.
Using myself and my friend as an example, we're both healthy, otherwise able bodied people with no apparent disabilities that we're aware of. Yet, my playthrough of Sekiro has been pretty seamless, while he has struggled and been discouraged from playing due to not being able to rely on co-oping for bosses. A feature we both took advantage of and used since we started playing through Demon's Souls together all the way back before Dark Souls even existed.
He loves these types of games, and has deeply enjoyed Sekiro before he inevitably runs into a brick wall with a boss. A boss that takes him twice as long as me, twice as hard as me, just to get through. For him, reflexes, and just general coordination are way harder when under stress. He understands all the systems and has been deeply engrossed in these types of games for a long time, and maybe with a lot more effort he might overcome these limitations and reach a similar skill level to myself, but the effort required to achieve this has not been fun for him. Beating a boss for him is not rewarding, but instead a relief.
One might say he just needs to get good and not play this like Souls or whatever. Well, he doesn't play it like Souls, he plays it like Sekiro, he just ain't that good. Then, with that revelation, one might come in and chime that well, maybe Sekiro just ain't for him. Well, I reply, he damn well loves the game. Lots of people seem to think that difficulty is the sole defining factor of a From-like Souls game, and that it is the core experience. It is most definitely a core experience, but it's not the only reason for why one might just like these really unique games. The hyping of the difficulty is in fact to me rather undermining of all the other incredible things the game achieves. Visual design, exploration (exploration so damn good I might add that literally no other game out there even itches that scratch for what a new From game achieves), the setting, combat mechanics (but not necessarily the daunting difficulty that comes packaged with those mechanics), the stealth, the story, the incredible world building and lore, the music, the characters, the animations, character design... All top notch stuff that people could absolutely enjoy in Sekiro without difficulty being a factor.
Now, thing here is I don't think Sekiro needs a difficulty mode. I don't think From gotta add a difficulty mode, and I absolutely agree overcoming the game is a wondrous feeling. But I also feel if a difficulty mode was added, an easy mode, or hell, an even harder mode for the truly crazed, that it would do nothing but benefit the game with more accessibility and more options for the people that need and want those things. The question here shouldn't be why Sekiro does or doesn't need a difficulty mode, but instead, why not?