I'm not really trying to 'refute' the original statement. Certainly, an LLM is just doing some calculations that can be done deterministically in principle. However, I think it's worth pointing out that there are practical barriers to doing those particular calculations both deterministically and efficiently. People who worry about LLM output not being reproducible aren't necessarily misunderstanding what an LLM is doing; they are responding to a real feature of most practical LLM implementations.