That's basically what I said. They are example generators. Their creators have not published the source of the data that goes in their training so we can assume that everything that is accessible from the web (and now from places that use their tools) was used.

So if you're already know the domain to provide the right keywords, and can judge the output to see if it's good enough, it's going to be fine. Especially, as you've said, it's something that you're used to do. But do you need the setup mentioned in TFA?

Most software engineering tasks involved more than getting some basic prototype working. After the 80% work done by the prototype, there's the other 80% to have reliable code. With LLMs, you're stuck with the first 80%, and that already require someone experienced to get there.