But when I'm playing D&D I'm playing a character with a class, a level, an Armour Class, a set number of basically consequence-free hit points, and a multi-page character sheet (which if I'm playing a caster has a large number of arcane rules). Everything is reminding me of this from the D&D mechanics in any edition.
And when you're watching a play, you can see the makeup, and the cardboard doesn't resemble the castle walls, and cast members move through the audience, and there's artificial lighting.
And when you're reading a book, you are holding a physical object, and reading a language you memorized, and puzzling out pronunciations, using a bookmark, getting papercuts.
These are just trappings of the medium. If you want to portray a person in armor on a stage, you put them in costume. If you want to portray a person in armor in a book, you write a description of the armor. If you want to portray a person in armor in a game of D&D, then you choose it as equipment and apply its effects to your Armor Class and whatever else it affects (encumbrance, speed, etc.).
If you are a person for whom the game is mostly medium, then you are someone that approaches with the usual audience assumption of "I am going to not worry about the trappings of the medium." Yes, the actor just appeared from offstage, but because I'm a willing participant in this little bit of make-believe, I am going to pretend that the character just arrived from a battlefield, because that's what the narrative is asking me to go along with.
You can tell a story without that story requiring ANYTHING but the visual in your head. You engage with nothing else except the spoken (or written) words, or the visuals and sounds presented to you.
You cannot play a game without engaging with the rules of that game. You have to actually pick up and throw a die, or tell a computer to do so. You have to actually add up a number. You have to actually tally experience.
Do you disagree with either of these things?
Mostly in agreement. I think there's some nuance that doesn't reflect the absolutes that are worth clarifying.
I agree that the only necessary thing for storytelling, in general, is your imagination. However, storytelling in various mediums means engaging with that medium. If you choose to tell a story with a painting, you're going to engage with paints to produce it (among other trappings of the medium, such as canvasses, brushes, even display locations like galleries or restaurants). If you choose to tell a story with D&D, you're going to engage with game mechanics to produce it (among other trappings of the medium, such as other players, dice, etc.).
I agree in principle that to play a game, you need to engage with the rules of the game. Those rules can be entirely in your head, of course. A game of tag has rules, but you don't need to do any math or random number generation to play tag. A game can be played entirely in your imagination. To specifically play a game of D&D, you do need to engage with its rules, which include dice rolling, math, etc.
I believe that D&D is often at its best when medium and narrative work together to support each other.