Your attempted redefinition assumes that once a person has been proven to act in bad faith in a particular set of circumstances he will act in bad faith for everything that he does in the future. In your scheme there is never any redemption. For people who are being punished to "teach them a lesson" it assumes that the lesson will never be learned, even after they have done their full time.
Firstly, I'm not redefining anything. Secondly, we don't punish people to teach them a lesson, bans (and blocks) are preventative, they are there to stop people doing more damage. Thirdly, there is a possibility for redemption, there just needs to be strong evidence that they've changed their ways. Just as strong evidence of bad faith can overcome an assumption of good faith, strong evidence of good faith can overcome an assumption of bad faith.