At the company I work for PiPs _usually_ lead to issues being solved. There are several developers I've worked with on PiPs (we do specific mentoring and follow ups on the areas of concern) that were able to improve and are now doing great. It isn't always a terrible thing, certainly not comfortable for the person on the PiP but it can be a positive thing in the long run!
Good on your company; PIP should focus on shoring up skill gaps or finding better role fit or invinting someone to take unpaid LOA to work through whatever life challenge they have.
BUT, I’ve only ever seen the “unattainable goal” type.
