I've heard that claim a couple of times now, but never read or heard experts in the field say anything like that. Do you have a source? Of course, you can do f

I've heard that claim a couple of times now, but never read or heard experts in the field say anything like that. Do you have a source? Of course, you can do fancy things with neural networks without fully understanding how they work, or why they behave like they do. But my impression is that common applications, like image classification, are quite well-understood now.