A prompt is everything to a LLM, there is no other interaction. It would be like saying that knowing the details of bash is snake oil for a sysadmin. If you are not doing some sort of prompt engineering, you are not making the best out of your LLM.
And sure, prompt engineering doesn't replace fine-tuning. To continue with the bash analogy, you can't do everything effectively with bash, sometimes you need to write code in C or other languages. But that you can write C code doesn't make using bash effectively snake oil.
A prompt is everything to a LLM, there is no other interaction. It would be like saying that knowing the details of bash is snake oil for a sysadmin. If you are not doing some sort of prompt engineering, you are not making the best out of your LLM.
And sure, prompt engineering doesn't replace fine-tuning. To continue with the bash analogy, you can't do everything effectively with bash, sometimes you need to write code in C or other languages. But that you can write C code doesn't make using bash effectively snake oil.