I don't understand this position.
LLMs are good at prototyping using data across _all_ similar projects that exist.
It is not a 1-1 copy.
Most frontend is a dozen components. Most backend again is a handful of architectures when it comes to DB/business logic, CRUD.
It goes to say that if you can guide the LLM to build something innovative you can think of, it will put those components together in a reasonable way - good enough to start off with.