Because it’s never the perpetrators that suffer. No child is born blind or brain damaged by rubella by a choice they made. They are born that way because of a choice that was made for them.
And those that perpetuate this unto children, when they suffer the consequences for their choices they fail to attribute it to their own misgivings. Instead they absolve their misgivings as the function of some deity who wishes to test their resolve. That this affliction is not of their own making but of some twisted logic test of faith.
No, this does not rid the world of those who would harm but it with absolute certainty harms those who were never given a choice otherwise.