Probably a function of how long it takes to get an Army pilot up to wings and then onto OCU compared to what the AAC actually need.
Once upon a time an Army pilot pitched up at Middle Wallop, did grading, basic and advanced rotary and then went out to the Field Army on Gazelle in a year or a bit longer if they needed Lynx course.
Think most of the worlds army aviation apart from the Australian Army Aviation Corps and us do not have fixed wing flying grading / EFT before RW Training.
Mind you look across the pond at Mother Rucker grads over the last half century ...they don’t have to go into fixed wing flying screening before training on TH-13/TH-55/TTH-67 and now UH-72A Lakota unlike their navy/ marine corps and Air Force brethren.
So are we moving with the times or going two steps back?
cheers