I wouldn’t have suggested it otherwise..
It doesn’t have the bad safety record of choke chains or long term pulling on flat collars.
No reputable study AFAIK has found a definate link between prongs and physical injury.
The images I’ve seen of horrific prong injuries have been images of dogs with embedded prong collars, the same injury will occur with any too small collar that becomes embedded.
It’s gruesome but it is not evidence of a dangerous product, any collar needs to be sized correctly and can cause injury if it isn’t.
Absolutely minimal pressure are used with them, certainly no harsh harsh leash pops or anything, you just curl your hand slightly, it’s a rare dog that pulls in one.
You don’t need to use it forever, they usually learn not to pull reliably in just a few walks.
Like any product they can definitely be abused but used properly I do not think them cruel at all.
I use one with my dog and she certainly isn’t adversely affected, she’s excited when it comes out and walks are much more enjoyable now for everybody.
Most people don’t like them because they look cruel and that is fine, use a harness then so the dog isn’t at risk of injury.