Old world curing can be done safely and my experienced curers do it a lot. I make my on Seranno hams and many fremented sausages from the old country. Part of the problem with doing it right is the fact that the unpurified salts of the old world are no longer available readily. But they can still be had from a few sources. Un-refined salts had more nitrates and nitrites in them naturally.
They are very nice products and persons possessing the correct attitude and experience can bang out some nice products.
Failure to study and understand the difference between old world salts and cures and the stuff presently sold as salt is the main reason for failure.