[jsnell]

But then Facebook would have had no incentive to offer the agreement to her. And she must have been very happy with what she got in the deal, given she gave up the option of talking about all the apparently horrible misdeeds she witnessed while they were still fresh, rather than a decade later.

[godelski]

Plenty of companies have nonenforcable clauses in their contracts. Either by momentum or stupidity. That's despite the inclusion of such conditions can often void a contract in its entirety.

Is there an incentive to have unenforceable clauses? Yes, of course. The same way one might be incentivized to say they will harm you if you do not do what they want even if they have no intention of harming you.

It's called "a bluff". Play some poker, you'll see how effective this strategy really is.