Roots of Blanket Forgiveness?

A lot of high holidays prayerbooks include the text (to be recited in unison):

I hereby forgive all who have transgressed against me, whether on purpose or by accident, whether by word or by deed. Let no one be punished on my account.

(I’m writing that from memory: I may be a little off)

Where does this come from? Why is it said? Does our tradition actually regard universal forgiveness as virtuous or wise?