That’s the question, but I don’t think there is a good answer.Just why is yoke so popular when it's such an inferior and flawed design compared with DIN?
Just because a system has been developed to obsolete an older design doesn’t necessarily mean that the old design is actually obsolete. And based on what I see in local dive shops yoke is not going away anytime soon. I bought a couple regulators over the past few years for my daughters. In both cases, what was in the shop were yoke versions. That’s what sells right now.
I had hoped that the introduction of the convertible valve would have accelerated the obsolescence of the yoke regulator, but that doesn’t seem to be happening anytime soon. Lots of yoke-only tanks out there and they seem to be hanging on.
I’d guess that the majority of recreational divers in this area aren’t even aware of DIN. I know that the divers I usually dive with (apart from my kids) had never seen a DIN reg until they noticed me assembling my gear.