Photographers have been arguing about cropping for as long as they've been able to do it. The camera, the film, and the paper, obviously, do not care one way or the other. As a practical matter, I try to get it in camera as close as I can because it saves work later. And there are aspects of the photo that can't be changed once it's taken. But to say to myself, once I get in the darkroom, I can't make any further editing to the photo, is just a mental block I have no personal need for. I reserve for myself the option of thinking about the image I want to make when I have the film in the enlarger. We frequently say here that the print is an interpretation of the negative, and there are many ways to do that. Arbitrarily saying one of several possible tools of interpretation is ruled out makes no sense to me. If you want to live with that stricture, and it works for you, fine, but I'm not going to.