I don't like the "artistic freedom" argument in general because that could theoretically be argued for developers doing problematic content.
Of course, this isn't the case with difficulty options, but just something to be mindful of.
As for the topic at hand, if FROM Software was interested in adding accessibility options, it would in no way hurt the difficulty because they'd be just options. When Celeste added those settings, no one stopped saying it was a difficult game or started saying it was easier. The only outcome of that was that more people were able to play it. I can't see any argument that convinces me that more people playing a game they want to is a bad thing.
Options are part of the game too. I think the fact that From Software hasn't added a discrete easy mode to their big action games from the last decade shows they recognize that. Not having any options (aside from the various builds and multiplayer system from the Souls games) means that everyone who plays the game has to go through the same type of experiences, roughly - everyone who reaches Anor Londo or the lordvessel beyond that in Dark Souls has shared similarly triumphant moments.
I think this is a big part of From's design ethos, and it's what their diehard fans are in love with - the strong mechanics, relatively high difficulty, and strong art design come together to make their games feel like cohesive, believable, dangerous adventures. Giving the player a menu option that simplifies the game would take away from that, and the fact that no such option is there gives their games character.
It's also worth mentioning that creating an easy mode so that people who wouldn't or perhaps physically couldn't play the game otherwise isn't really "letting them play it". Games are mostly made up of their mechanics, and the way learning to interface and interact with them sparks your brain into action. Creating a simplified, less-potentially-engaging alternate mode for your game isn't necessarily letting more people play your game; it's just creating a subgame on the side.