alt Hacker NewsIt would be "its own" in that it's customized for the specific use case.
Your same argument could just as easily be applied to humans. If you write your own code, is it really your own, or is it just based on your own training and other code you've seen?
I think their point is that there is no new invention here, being able to mimic what a human will do is absolutely impressive, but at the same time it is still mimicking humans. While I just type that out, I do realize my expectations for AI has been constantly lifted by how fast it iterates.