Similar arguments could have been made against deep (multilayer) neural networks (DNNs) for a couple of decades. No one knew for certain in the 70's and 80's i

Similar arguments could have been made against deep (multilayer) neural networks (DNNs) for a couple of decades. No one knew for certain in the 70's and 80's if DNNs would pay off, yet a handful of then-obscure researchers persisted. And for quite a while DNNs were kind of a research backwater -- some researchers moved to Canada because they couldn't get funding anywhere else. As a close approximation, "almost no one" was interested in DNNs until Alexnet won ImageNet in 2012. Just because we don't know which research directions may or may not pay off decades from now does not mean such directions aren't worthwhile and should be abandoned.