It seems likely that this will help some doctors in at least simple cases, but natural frequencies don't 'compose' well if you are doing multiple tests; you can

It seems likely that this will help some doctors in at least simple cases, but natural frequencies don't 'compose' well if you are doing multiple tests; you can't use them to compute posterior probabilities when combining a half-dozen different tests, at least not without involving impractically huge numbers or fractional people. Moreover, the trend in modern medicine is towards combining binary/categorical tests with a range of distributions based on age, gender, race, genetic factors, vitals, continuous lab result values, etc. Yes, we can theoretically delegate some or all of that to software, but that is true for medical diagnosis in general; while we're not there, doctors must understand and perform these calculations. So it seems fine to use natural frequencies to help out, but building Bayesian intuitions early and often seems a better path.