That's not necessarily true. Vibecoding a simple JSON -> YAML converter to translate a 2MB JSON is going to be much cheaper than including that JSON in a prompt and burning hundreds of thousands of tokens. Besides, there's lots of cases where the math simply favors a bigger one-time cost rather than paying fees in perpetuity.
Even today, an advanced AI model will realize exactly what you said, and generate a script and run it behind your back to save the costs and ensure correctness. To me, that's still using the agent directly, not vibe coding. No app gets developed in the process, and if the agent doesn't tell you, you won't even know any coding took place.
With the caveat that literal today's models are not allowed to run code themselves but instead give you the code in the chat window and ask you to run it yourself for security and safety reasons. But the capability is there.