There have been assumptions about supply chain sources that may not apply to these circumstances. The hose material in question was produced by Goodyear Engineered Products a US firm previously a division of Goodyear and recently acquired by ContiTech, a German industrial products firm. Given their long history, it’s reasonable to assume Goodyear understands how to engineer and manufacture rubber hose. DaniCorp, a US firm, has been supplying finished hoses to both the original equipment manufacturing (OEM) SCUBA market and to wholesale distributors serving the local dive shop market for nearly 30 years. It’s likely nearly every long-time diver in the US that has purchased a replacement rubber hose in a dive shop has received one or more DaniCorp hose assemblies. From information available to me, Danicorp is no longer accepting purchase orders and may have ceased production entirely with an expectation they are shutting down.
What is most disturbing, it seems probable there are a lot more of the substandard low-pressure rubber regulator hoses within various SCUBA diving retail channels who are also probably unaware of the issue.