It's not just better than a blind man. It's better than any human, once you scale the task up beyond a certain point. Consequently, we should not get hung up on the path taken if the ultimate goal is the best possible care for patients in our overloaded public systems. And this paper suggests there is great potential.
Although I would tend to say we should expect machines to be significantly better than the average doctor. Before we role them out to everyone we should require them to be at least as good as the top 10% of doctors, I guess.
But regarding diagnosis, there are symptom checkers where you feed stuff in. I get the impression that multiple companies are in the process of building such tools based on crawling research papers to diagnose even very rare conditions. IIRC IBM Watson had such functionality.
I mean, it's not like rocket science. More like investing the effort to build a really big decision tree.
[1] Sure, you have to test your new cancer drug on actual cancer patients, but why include the 65 year old obese patient, when you could instead include the 32 year old triathlon athlete into you cohort?