[Discussion] What are the problems of the backpropagation algorithm? • r/MachineLearning

Two days ago, an article quoting Hinton who was saying that backprop is not necessarily the way to go for AI, generated lots of very cool discussion on this sub-reddit (here). In this discussion I would like us to answer the question: what are the problems of backprop? Indeed, the article didn't really answer this question, only referencing shortly to the difficulties of unsupervised learning. Here's my initial input: Problems that seem to be intrinsic to backprop: Problems that currently pose lots of difficulties and we're not sure are possible with backprop: Do you agree with these?