If I had to take a wild guess it would be... -- The system and rules that 3dgs was built under may no longer hold true with newer GPU design and on-board programming - This may mean that you GPU gen or even more current ones now use better systems to run the transparent pass, as this would be a logic place for each gen to improve optimization.

Other notes begin that using transparency and solid pass are pointless opposites and my lead to more work as the system or shade-c attempts to set-up alphatest/alphablend and then drop down to a solid pass. It's like saying "You must be transparent" but then saying "you must be rendered none-transparent. "

But hey guess is fun right... I wonder what it feels like to actually know... hehe