> How are people supposed to learn and improve without knowing told what they did wrong?

To shove this back into the 'online community' context, there are certain people who have no interest in learning what they're doing wrong; or even who fully understand that what they're doing is wrong, and have no interest in improving.

Examples: spammers, trolls, and the willingly-obtuse-slash-rules-lawyers (who are slightly separate from trolls, but are similarly un-educatable).