LLMs are not very predictable. And that's not just true for the output. Each change to the model impacts how it parses and computes the input. For someone claiming to be a "Prompt Engineer", this cannot work. There are so many variables that are simply unknown to the casual user: training methods, the training set, biases, ...
If I get the feeling I am creating good prompts for Gemini 2.5 Pro, the next version might render those prompts useless. And that might get even worse with dynamic, "self-improving" models.
So when we talk about "Vibe coding", aren't we just doing "Vibe prompting", too?
If you run an open source model from the same seed on the same hardware they are completely deterministic. It will spit out the same answer every time. So it’s not an issue with the technology and there’s nothing stopping you from writing repeatable prompts and promoting techniques.