I don't think it needs to be this complicated.

Every product at Google is being pressured intensely to put AI everywhere. The focus is on velocity, not well thought out product experiences. This sort of photo editing interaction is not novel so it doesn't require a ton of out of the box thinking to decide to add it to Photos.

Google is worried that other companies are going to steal their lunch and their approach is to try to throw every AI feature they can into their products as fast as possible.