Oh dear god. I'm proof reading some of my stuff right now, and I'm not sure how in the hell I can fail to notice the number of words I simply drop out of sentences when I write. It's really rather disconcerting. Either my brain or my fingers is like a sieve, and they have no clue when they're being messed with.
I've noticed it when in your games, and it's OKAAAAY
I've seen that too in many people who do write walls of text (and know it myself from my few forays into writing, like my RtD or the other one I continued past another person's, and wrote about fundead stuffs.) The reader usually replaces those words with contextual analysis anyway, and it is usually implied that it's not intentional on the writer's part (also because of spellchecks and silly roboots can make mistakes too!
)
That happens at times because of the large amount of words in mind, and at times when we are fatigued in a significant amount, we can sometimes replace words we use with other things lurking in the subconscious.
...Which reminds me of when I wrote hippopotamus instead of hippocampus in my notes while being REAL tired back in my MedTech days. Only noticed when re-reading them for study and then I recalled 'oh huh, my mind was drifting to analogies...'. Because sometimes, imagination also gets in the way.
But also sleight of thought.