Anyone uses the backpack leash for their toddlers? Yay or Nay?

I have a friend who uses it and swears by it. His son refuses to be carried or being held by the hand and to make things worse he loves to make sudden dashes while waiting for the traffic to stop. So for safety benefits which outweigh the moral arguments, he practically HAS to use it. We can't judge every parent's decision as our kids are all different and we do our best to keep them safe. That's what's most important.