> Telling somebody that they're fucking up and that they need to improve is one thing,

In my experience it's management telling the employee they're fucking up when in reality it was management fucking up the whole time. Unrealistic schedules, untenable goals, poor/no feedback or guidance, or just actively burning the employee out. Management then uses the PIP to fire the employee without a lawsuit.

There's never a good faith position of management with PIPs. They're for their benefit and never the employee's benefit.