A punishment larger than the harm can create a second injustice.

Excess punishment does not add justice, it adds harm. Once the response is out of proportion to what was done, a second wrong has occurred, and it tends to produce defensiveness rather than repair, which means the original harm gets less attention rather than more. The severity ends up protecting the offence.

When setting a consequence, size it against what was actually done, not against how it felt or how it looked. Proportion is not softness. It is the thing that makes the response credible.