Those of you that are against the leash, do you have children? Have you ever lost your child for even 2 minutes in the grocery store? Or had them within 2 seconds get away from you and run into a crowd, or worse in front of a car?
Some parents feel that using leashes is actually less restraining than keeping kids cooped up in a stroller all the time. They provide freedom to roam around, but allow parents to control boundaries and limit danger. They significantly reduce the risk of children wandering away from parents, into the path of danger. For parents of multiples, it can be a very effective way to keep kids from disappearing in different directions.
The leash is not a collar around the neck, it is a specifically placed harness for different ages with padding. Pediatricians have said that they actually have prevented some of the injuries from pulling up a child, hanging onto a child etc. Usually shoulder injuries and along with other arm injuries.