Subtext is not theme, everything people write has subtext. When someone posts on the internet we can often tell if the person is angry or happy or depressed even if they are not being overt about it, we get that through their subtext. A writer like Stephen King is not a great writer by objective literary standards but he is an effective writer because he understands subtext, he knows that fear is not just one thing, there are gradations of fear, there is the fear of tomorrow, the fear of loss, the fear of death, the fear of being late for work and there is the childhood fear of the monster under the bed. King knows he can exploit the common everyday fears everyone has to build that into an irrational fear of something that may even be absurd out of the context he provides. AI lack this and is a very long ways from it.

Romance is overflowing with subtext. No idea about lit_rpg, never read anything of that sort but I am sure it is there. Even your short post is ripe with subtext.