The idea is that by spending a few minutes with your card, someone can now clone it and impersonate you. Yes, they could already steal your card, but you might notice that. But if you leave it on your desk for a few minutes in your wallet, or IT “borrows” it to re-encode it, or any thousand of other ways to get a hold of your RFID card… it can be dumped, cloned, and you can be impersonated.
That’s the threat vector.