Earlier quoted context omitted.
You have to start with toy models before scaling up.
Achieving 2020 is an example of a failed toy model, not a successful toy model. Almost any ML algorithm can be thrown at CIFAR10 and achieve ~60% accuracy; this ballpark of accuracy is really not sufficient to demonstrate viability, no matter how aesthetically interesting the approach might feel.
But "any ml algorithm" isn't the point. It's a new optimization technique and should be applied to models/architectures that make sense with the problems they are being used on.
For example, they could have used a pretrained featurizer and trained the two layer model on top of it, with both back prop and FF and compared.