I think it's related to my ADHD. Reading is very difficult because as I read, my voice just completely wanders off, CONSTANTLY. "Oh hey, 'gargantuan' that's a great word. Reminds me of a video game monster... Oh did you just read 2 whole pages without absorbing a single bit of it?"
To add a bit more commentary: this is the one time I consider my ADHD to be a terrible disability. I cannot read. I just can't. Grad school was HELL when I had to read. But my ADHD and associated strong independent inner monologue is immensely powerful when I'm trying to solve problems myself, such as doing software design.
The only time I experience the sort of word-based hijacking you're describing is with what I think of as "internal argument". I'll think of a previous or possible future discussion and structure my reply in words. Although since words are slow, often the words will sort of collapse and I'll shift to sort of a mental outline mode, where it's more a feel of structure with occasional words or phrases cropping up.
The Origin of Consciousness in the Breakdown of the Bicameral Mind Paperback – by Julian Jaynes
And yeah, I can have conversations with the voice. Yeah, it can help to focus moving my thinking forwards on some problem-solving thing. But, alas, often when I'm doing that it just starts saying obviously-silly things, as if it's a Markov model. Sentences that might sound structurally reasonable but that are obviously not what I meant to say/think, and obviously not true.
But it almost never interferes with reading. Reading is too compelling. Even if my thoughts go off in some other direction while reading and I do the "just read a page but absorbed nothing" thing, there's no voice involved then, it feels like a different process.