An NDA would not and could not cover abuse, and I highly doubt it covers your impressions either (e.g. "it was terrible and the interviewers were all rude!"), so I don't really agree with your first point. For your second I can see where you're coming from, although at least in this case I don't see droves of people interviewing and then saying the process was terrible. But there should be (and perhaps is?) an easy way to complain about bad interview practices companies have without running afoul of their NDAs.

For your third point, I don't understand what you're getting at. What logic are you referring to that is broken?