If you mean the lack of theoretical guarantees due to a highly non-convex optimization, you could argue the same thing about 30 year old 2-layer networks. And we actually do have a decent idea why deep learning works well:
Re:What’s Next for Artificial Intelligence
by mathgenius on Friday August 19, 2016 @06:36PM
(#12324018)
Thankyou that looks awesome.
Btw, "why" questions are always a bit ill-defined, it's like asking for some kind of narrative to satisfy the questioner. "well in the beginning there was the big-bang..." So anyway I'm quite impressed at these papers.
When I read this I interpret it to mean they have no idea how deep learning works. (More specifically: why it works as well as it does.)
And the part about being modeled on the human brain just seems to be a fortunate (?) coincidence.