Well, I made myself the same question the first time I met a diver following DIR rules. He did know the method very well, but was entirely incapable to explain me the reason of many technical and behavioural rules he was following very obediently. He was simply trained that there is only ONE right way: the DIR way (which by definition is "right") and any other approach is wrong.
So I started reading on the topic, and discovered the explanation for many technical and behavioural choices, which were sensible in the context they were developed. The point is that they are not the only way to face some problems typical of extreme environments (such as caves and wrecks), and furthermore, in a different environment, other technical choices are possibly better.
Just think about the famous "frog kicking" and the Jet Fins. It can be effective for moving slowly in still water in a tight enclosed space, where the bottom is covered by mud and sediment and you do not want to raise it. It is entirely wrong in other situations, for example at Maldives inside a channel in the barrier, where the water flows like a river, and you need long, powerful fins, and the most efficient kicking available. Same about keeping your hands partially stretched in front of you. Again, good in a cave, so when visibility is limited you hit the rock with your hands and not with your head.
But it increases significantly the drag, better to assume a more hydrodynamic position if you want to swim fast in an open, obstacle-free environment.
Or this emphasis about staying horizontal in any case. When you dive along a vertical wall, here in Mediterranean, covered by Paramuricea and red coral, and with deep cavities with lobsters inside, you manage yourself much better staying perfectly vertical. It will be easier to look inside the cavities without over stretching your neck, and making photos at the critters.
Also the long hose is a requirement inside a narrow tube-like passage, but it can just be a problem in open water, as it allows your buddy in distress to reach for the surface staying above you, filling his BCD and pulling also you to surface too quickly. A hose of more reasonable length (my secondary yellow hoses are 1.00m, my primary is just 0.75 m) forces the buddy to stay in "face contact" with you, and you will be able to grab the control of his BCD if he is using it improperly.
Conclusion: while sensible for the specific usage they were developed for, all these "technical" rules, equipment and behaviours should be evaluated for the context where you are diving, and for the buddies who dive with you.
It is wrong to consider them as religious rules, to be followed always without reasoning.
And to consider people making different evaluations and choices to be invariantly "wrong", because only DIR is the "right way"....
