What the actual fuck.
For christ’s sake, people. It’s a medical device, not a toy for people with unruly children - just like you don’t toss a straitjacket on your spouse every time they raise their voice at you. It’s used for kids who don’t have the ability to control their actions either due to physical or mental conditions in order to keep them from seriously/permanently injuring themselves and others. Say you’re in the ER and you have a panicking kid with a rapidly bleeding wound. Do you have any idea how many people it would take to hold that child down for treatment? Do you know what kind of injuries they and the child can sustain during that? Alternatively, there’s a velcro restraint that can hold them safely in place for treatment and it takes 1-2 minutes to get it on them so treatment can get started. And yes, they make them for adults as well.
If you can’t figure out why such a thing would be necessary, then I’m glad you’ve never had to deal with any situations that would require that. Other people do have to deal with those situations, and this is better than the alternatives. If you still don’t get it, go ask an ER nurse for a full list of situations where this would be needed.
Sanity wins again.