LLMs are generative and do not have a fixed output in the way past autocompletes have. I know when I accept "intellisense" or whatever editor tools are provided to me, it's using a known-set of completions that are valid. LLMs often hallucinate and you have to double-check everything they output.

I don't know what autocomplete you're using but mine often suggests outright invalid words given the context. I work around this by simply not accepting them

The high failure rate of LLM-based autocompletes has had me avoid those kind of features altogether as they waste my time and break my focus to double-check someone else's work. I was efficient before they were forced into every facet of our lives three years ago, and I'll be just as efficient now.

Personally, I configure autocomplete so that LSP completions rank higher than LLM completions. I like it because it starts with known/accurate completions and then gracefully degrades to hallucinations.

Because they are not. Autocomplete completes the only thing you already thought. You solve the problem, the machine writes. Mechanical.

LLMs defines paths, ideas, choose routes, analyze and so on. They don't just autocomplete. They create the entire poem.

Sometimes. Usually LLM does exactly what I ask it. There is not like there are million ways - usually 4-10.

Who'd want an autocomplete that randomly invents words and spellings while presenting them as real? It's annoying enough when autocomplete screws up every other ducking message I send by choosing actual words inappropriately. I don't need one that produces convincing looking word salad by shoving in lies too.

I wonder why people have such completely different experience with LLM

You could build one like that, but most implementations I've seen cross the line for me.

Hard to define but feels similar to the "I know it when I see it" or "if it walks like a duck and quacks like a duck" definitions.

Autocomplete annoys me, derails my train of thought, and slows me down. I'm happy that nobody forces me to use it. Likewise, I would greatly resent being forced to use LLMs.

Completely different context though - you have to feed through your own data for autocomplete and even then it’s based on your own voice as a writer. When you no longer have to write - nor think about those things you’re writing - then your voice and millions of others will be drowned out by LLM trash.