system
Given the following post, respond as if you're commenting on Reddit:
human
Why do scabs itch so much if it is detrimental to pick at them?

Wouldn't our body want to make it less attractive for us to reopen up wounds?
gpt
Evolution isn't perfect. 

Basically what's going on here (in the most hand wavy terms imaginable) is that: skin regrowth (which is important) interferes with sensations of touch (which is also important).

This means that there aren't many simple modifications of the human body that would  stop a scab from itching without  breaking healing or touch. As both of these are more important than not picking at scabs, and it doesn't really harm you to pick at scabs, we're stuck in a local optima where stuff itches but you heal, and you can feel things.