I am not aware of this setup, and so I’m musing and winging it, but I think what they’re saying is that if you point at the paper and say “is this a sheet of paper” they’d say yes. And then you point to the crease and say “is this a crease” and they’d say yes, so it has identity, separate from the paper (as in creases and papers are not synonymous), but given that it’s not counted when listing things in the room, it’s also not a thing.

But I think for me it’s not that tricky, because it’s a feature of the paper. Like if there was a coat in the room with buttons, and you asked me what was in the room I wouldn’t say a coat and three buttons, I’d say just a coat. And the coat has three buttons, but those are properties of the coat, not the room. And buttons are something that can stand-alone!

But if I had a sheet of paper with a button placed in the middle of it, but not attached, I wonder would most people say it was a sheet of paper and a button, or a sheet of paper with a button?

Creased is just a different way for the paper to be for a little while.