I absolutely love autocomplete in VSCode but hate it in Visual Studio while using the same LLM. The big difference for me is the function AcceptNextWord which Visual Studio doesn't have. A long autocomplete suggestion is rarely completely correct and becomes an annoying distraction but one or several words at the beginning of the suggestion are often correct. So, I usually accept only one or few words in VSCode with a hotkey, then type a bit more, then accept few words more etc. That works great for me. Also, I developed intuition in which pieces of code an LLM suggestion would be most probably useless, so I just ignore any suggestions there to avoid unnecessary distraction.
My guess is that many devs who don't like LLM autocomplete, are just unlucky to use a suboptimal UI. As an example, I personally don't understand how some people could like autocomplete in Visual Studio. As you said, it's just too distracting and irritating.
BTW, I use Codeium, not Copilot. But I guess they should have the same autocomplete UI which depends more on IDE than LLM.
This mirrors my experience with it as well. Autocomplete is just way too distracting for me, and I could end up writing the code faster myself without having to proofread every suggestion it throws at me. I ended up turning off autocomplete as well and instead use the copilot chat feature when I need it.
Perhaps I'm just an old man telling the LLM to get off my lawn, but I find it does bad things to my ability to concentrate on hard things.
Having a good sense of when it would be useful, and invoking it on demand seems to be a decent enough middle ground for me. Much of it boils down to UX - if it could be present but not actively distracting, I'd probably be ok with it.