>PIPs are intended to bring consistency and fairness to the way employees are judged and managed.

That's mostly bullshit. The real purpose of a PIP is just to bolster documentation on the employer side to fend off any wrongful termination lawsuits. It probably has a side effect of looking more consistent, but that isn't the purpose.

One thing that does favor the employee is that legal and HR sometimes get carried away with how much documentation is needed. So it ends up taking longer than the employer really wants. But if the employee understands the true purpose of the PIP it gives them plenty of time to job search.

It also help quell fears from other employees about their own job.

"There was a process, EmployeeA didn't improve." rather than "EmployeeA was suddenly terminated yesterday"