I think you’re getting downvotes for the statement “never been shown”. It’s an overly broad claim, and even the link you posted talks more about the severity of punishment being a weaker deterrent than the certainty of being caught (and punished). There’s still no doubt that if theft was suddenly not punished at all then there would be more theft.

From other reading I’ve done the consistency of punishment is more important, and it’s better for criminal justice systems to provide a certain small punishment than an inconsistent outsized punishment, and this has a lot to do with the way humans evaluate risks, and improved paths towards helping criminals becoming non-criminals.

Anyway, I learned a bit from the link you posted, mostly that this sort of thinking is mainstream enough to be presented like this by the DoJ. So have my upvote.