LLMs are definitely probabilistic. But that doesn't mean that you'll always get random results from them. In my normal usage, I can get great results out of it because I give it absolutely zero freedom to think on its own and fully constrained tasks.
It's when you give it even a little wiggle room, or in the vibe coders' case, nearly unlimited freedom, that they hallucinate and mess up. The psyop is in this later case: that the LLM is better than you if you let it think for you. And that's simply not true for anyone.