AFAICT this is a fear that some game developers have, that someone will steal their game and run with it, and the stories told are more repeated based on this shared fear than based on realistic scenarios. People repeat it because it’s a good story.
And yes, I’m aware of some situations like 0x10c and the like.
More specifically to AI... A blog on a nice website is no longer a signal for quality so there's just no point in devs investing in that.
The idea is not valuable, ideas are a dime a dozen. The actual value is in your implementation.
It requires discernment, taste, on the part of the user to be able to point the LLM at the weird parts that look wrong.
Even with that, the LLM can only fix most of, not all of, those rough edges.
There's no moat in an idea either so I guess it's down to marketing budget.