What a wonderful write-up, and I definitely agree - I met some peeps on reddit through the lfg subreddit to play D&D and we all immediately clicked, have been doing Phandelver (the beginner campaign) over Discord (together with some homebrew one shots written by our DM) since August or so. There's really nothing else like it.
I have been playing some WRPGs / immersive sims recently and something that came to mind is that the western RPG design philosophy, with its emphasis on choice and consequence, seems to be focused on emulating the function of a DM. The best games of its kind (i.e. Deus Ex, Fallout: New Vegas) mold and shape the world based on your actions the same way a DM would depending on what what your party decides. We just accidentally killed a key NPC in our storyline, for example, so I'm super excited to see how our DM decides to deal with it for our next session.
Where there is a divergence, though, in my opinion, is that video games are inherently replayable - so part of the appeal is viewing the story again and making a different decision to see what would happen, and experiment with that - whereas with a tabletop RPG, it's all about maintaining the illusion of your actions being permanent and irreversible.
Anyway, that's just me rambling - just thought it was interesting seeing how D&D seems to have influenced a lot of video games that I enjoy!