I don't think it's controversial to say that early editions of D&D had a number of mechanisms that were internally at odds with creating "immersive" play experiences. Not to say that you
couldn't immerse, just that there were lots of artifacts getting in the way.
- Gaming the "XP is gold" system, as noted by many.
- General lethality / assumption of "troupe" play meant it was dangerous to get attached to any one character, let alone try and "immerse" as one.
- The massive amounts of procedural rules (time, mapping, wandering monsters, massive numbers of tables on which to roll).
- Gamist resource management of all sorts (rations, hit points, consumables, treasure hauling).
All of these are aimed at pushing players towards "skilled play" kinds of behaviors, of the kind predominant from '78-'83. And there's nothing wrong with it, it's just that taken at face value, they're largely at odds with "immersion" as a concept. The general "win conditions" of skilled play have no direct avenue into "immersion."