It’s just a term that signals “completion in between” rather than “after”. Regular code completion usually doesn’t take the following blocks into account mostly because these are grammatically vague due to an ongoing edit.
Your comments may be sympathised to, but why on earth are they addressed to the root commenter. They simply shared their findings about an acronym.
Because they mentioned it, why on earth would you think that is not a valid response in a thread that mentions it, from my observation that's pretty much how forum like threads work.
More pressingly why do you think you should police it?
Autocomplete is the feature, fill in the middle is one approach to implementing it. There are other ways to providing it (which were used in earlier versions of Copilot) and FIM can be used for tasks other than code completion.
It's like everything to do with LLM marketing buzzword nonsense.
I really want to just drop out of tech until all this obnoxious hype BS is gone.