What you do see in there is this:
I see a guy saying don't try to solve skills problems with gear. People get too hung up on gear ... that's only a tiny part of what DIR brings to the table. People get all defensive when they think that because DIR promotes a standardized rig that means they believe everything else is inherently unsafe. I don't think that's it at all. There's a big difference between "not optimal" and "unsafe" ... and I think that for the most part, they're talking about optimization.
DIR promotes gear standardization for a lot of good reasons. However, let's be real ... none of those reasons are because they believe their way of doing it is exclusive to diver safety ... and in particular not to every applicable way of diving. As I said earlier, standardized gear makes dive planning and execution easier ... and the more complex the dive, the more important this becomes. On a tropical reef, it really doesn't matter ... the environment is very forgiving, and the gear configuration is standardized toward both the environment and the needs of the diver. Different environments ... different needs. You know as well as I do which environment the DIR agenda derived from. Whether that agenda benefits you depends a great deal on where and how you choose to dive.
At any rate, I don't see the quote you pulled out as saying that non-DIR configurations are, by definition, unsafe. I see it as saying (a) don't solve skills issues with gear ... (b) make configuration choices that are logical and serve a function ... (c) don't load yourself down with a bunch of gear you don't need.
Those tenets are not unique to DIR ... in fact, they existed long before GUE ever coined the term.
I have heard in the (admittedly distant past] people citing this as the reason you do not dive with anyone whose gear is not configured in the accepted DIR fashion (the only one that makes sense), which means about 95% of the divers in the world.
A one-time frequent SB poster who is now gone used to say with some frequency that all alternative air regulators carried in the popular "golden triangle" position always come loose and drag in the silt (apparently even when there is no silt), get fouled or have torn diaphragms, so that they never work when actually needed. Logically, such a diver is a stroke, because that diver cannot not give you air when needed.
I am not saying this is a common statement today, but I have heard it in the past.
Well, you have to take what you hear people citing in the context of who's saying it.
I hear people saying things on ScubaBoard all the time that just make me wonder what in heck they're thinking. I hear people quoting things as PADI standards that don't have any basis whatsoever in what PADI teaches. The internet is full of misinformation and personal opinions. Am I to hold that against the agency?
I don't think so.
... Bob (Grateful Diver)