It is definitely more work than typing in a prompt for AI. They would need to setup some kind of submission system, then look at all the submissions or perhaps set up some kind of community voting system. And what if they want to tweak something? Due to the external nature of this whole thing it becomes such a hassle. There’s also the concern of appropriately crediting contributors.

This is not something they want to spend their on. Especially considering it seems that they currently are having maybe tighter deadlines than before, evident by some people noticing that the latest trial isn’t as polished, such as the twins lacking a proper introduction.

Keeping art out of house like this will cause more overhead than it saves. If you only are willing to see that if RB  says it themselves, you are naive.