They’ve gone on record a few times saying PTR is only for bug testing. They don’t believe PTR is a valid place to discuss balance as so few of the player base actually try it. With that being said, everytime something has been too strong, people have called it out before it came to live and became a huge problem. It started with Iron Clad bastion and these things are still being caught to this day. Personally they really should consider the feedback around balance they get on there.
Even more so since a lot of bugs that get talked about on ptr don’t get patched out either.