The issue is not stealing the idea itself. The issue is stealing the work in its entirety - as is - with all its flaws and character intact. That's what makes art unique, right?

I would think the same goes for codebases too. On a personal note, I wrote a CMS in Elixir from scratch way before even AI was a thing. It uses a lot of proprietary flows to make it scale, helping it serve millions of requests efficiently. I certainly did not give OpenAI nor Microsoft permission to steal my code. And yet they did. Is that not theft of my Intellectual Property?