> ML hasn't done anything new since the 80s

Schmidhuber, is it you?

But seriously, it's partially true most techniques we use today could be found initially envisaged in 90th ANN-related papers. I think Geoffrey Hinton summarized most of them well in his famous "Neural Networks for Machine Learning" lectures. Essentially, what is available today is compute resources unimaginable in 90th, so scaling up from a shallow 2-layered Multi Layer Perceptron to something like 96-layered deep architecture is possible only recently. We also found some of the tricks work better than others in practice when we scale up (like *ELU non-linearity, layer-norm, residual connections). What stays the same however is the general approach: training and validation sets, cross entropy loss, softmax, learnable parameters based on data-in/data-out training pairs, and differentiation chain rule. IMO this requires some innovative revision, especially generalization is still very weak in all architectures today.