It's not really that generous. If they put you on a PIP they want you gone, but it may be a few months before they get rid of you. And if they do eventually need to fire you, you're still probably going to get severance. It's cheaper for them to just give you the severance up front and not have to pay you for any additional months spent working

Also I don't find the concept of the "jury" that generous either. In fact it's pretty weird and seems like it could become extremely political. There's the fact that the person advocating your dismissal is potentially the boss of the people advocating that you stay, which creates a pretty severe conflict of interest. There's a potential factor that a team needs to downsize, and by advocating you not being on a PIP the members of the jury risk themselves being put on the PIP. And of course there's all sorts of problems with whether you're well-liked or not by people in the office for reasons not relevant to your work