Sorry, but not being of immediate British ancestry, nor having been presented with any reason why I should regard their armed forces as authorities on sartorial matters, I see no reason why that tradition should be of any relevance to myself, or really, any average person trying to decide how to thread his belt.
It's not out of ignorance that I choose to thread my belt one way or another, but a matter of practicality and logic. Gee, should I thread my belt in one direction in a quick, familiar motion that affords my natural hand dominance, or should I spend several extra minutes awkwardly pushing it through another way because someone is going to browbeat me by saying that the British Army demands I do it that way? Getting worked up about how other people thread their belts is what I find "retarded."
The basis of all pointless arguments-scramble for any reason to justify your original position regardless of whether that was the reason for your original decision.
Regardless of you unfortunate heritage if it takes you several extra minutes to thread a belt, perhaps you are the retard?