Why is there so much Debate in DIR?

In all the standard dive training, one message is very clear. Do not dive with a goal or mission orientation as it will cloud your judgement. This is a basic protection against photographers sucking their tanks try trying to get the last perfect shot, lobster hunts wrestling out the last bug or the spear fisherman getting in the last shot.
But what is you do want to accomplish a goal underwater and you are not a commercial or military diver?

An individual can only do so much with technology. Eventually they need to help of another individual. As people and equipment are added, so in the complexity. Therefore it becomes simpler, easier and more efficient to streamline training, equipment, and responses to accomplish the goal.
If you have no team and no goal, then you have no basis to be DIR. Individuals debating D ring placement outside of the context of a team with a mission, is time wasting folly.
GUE is simply the most consistent training organization. But even their instructors (I've had 4 so far and are Friends with others) have various in how and what they teach. Their background or team will set the context for the difference.
An diver or dive team has to decide which is more in context for him or her and the team they dive with.
GUE Tech 1 is taught with the small Halcyon Surface marker as an acceptable lift bag and surface marker. This is DIR.
I dive with a team off South Florida that bombs wrecks and shoots a lift bag upon drifting off. The small Halcyon marker is not big enough to been seen at distance in rough seas. Our team has decided that the Halcyon Semi-closed 60lb lift bag is the preferred choice for a surface marker. Every team needs one. The small Halcyon marker is not allowed on the boat.
This is DIR to us in the context of our team and our mission of exploring wrecks.
To another team (I'm making this up to prove a point) say, surveying fish off the shores of Bonair, the small surface marker may be just fine and there is not need for a larger lift bag to accomplish their missing. Hence it is DIR to their team and purpose.
The debate is always about the "small" details. The big picture is that a well trained DIR diver can take their equipment and go from South Florida to the Great Lakes or Truk Lagoon and dive with other DIR divers with very little time spent getting up to speed on those smaller differences. Team in those regions will have already figured out the best way to dive those areas.