This is an important point, although I can imagine AI could be trained to spot things that don't belong or are unusual provisions in an NDA. This may be what you're getting at, but it's easy in a contract review to focus on reacting to what's there and it's harder to know what's missing. An NDA is a relatively simple, cookie-cutter types of agreement with widely agreed elements. Other agreements not so much. How would AI figure out what's missing?
That's an important point, but I assume an AI would use some sort of checklist, perhaps seeded by human lawyers, to spot expected-but-missing provisions.