Lemon showed this last night on stream, late game USF is about support weapon spam with indirect fire and Jackson's. Riflemen do bleed a lot late game, which is why you don't replace any losses above two squads and instead use 50 cals and Pak howis which will not bleed you nearly as much. Priests as well deal with Pak walls and mgs late game.
People aren't playing USF the way they should be in the new patch, they should go back to the drawing board.
Even if this is done for 1v1 specifically eventually pak walls with support can take out your jacksons even at range and lmg gren blobs can insta-snipe support weapons and take them for themselves. Thus leaving you with late game rifle squads to eventually bleed you to death.