I've never seen a jockey wheel that used the bolt's shaft as a bearing surface, hence I've never seen a jockey wheel that requires an exactly matching bolt.

Nothing went over my head; you say the size doesn't have to be spot on, and I say it can be miles off as long as the pulley and chain have clearance (many MTB derailleurs have huge jockey wheels that can be replaced with much smaller ones in a pinch).

Obviously the correct parts are preferable, but questioning the standards of someone rightly saying this area isn't critical is a cheap shot and pretty lame, IMO. I could perform every kludge in my book on your derailleur and you wouldn't know a thing from riding it 5000km.