Why is it bad to be a tattle tale?

I have three boys, 6, 7 & 8, all 10 months apart. I should note, my 8 year old is autistic, heavier than the other boys, and plays pretty rough. I need to know when someone is getting hurt, I need to know when someone is getting blamed for something that isn't their fault. With bullying in schools as bad as it is, neighborhoods full of gun violence where no one will act as a witness, why are shunning somone telling the truth? via /r/Parenting http://bit.ly/2DIYEVb