Well, that type of bracing was done for both drag racing and road racing.
Above is the Yoshimura Wes Cooley Suzuki Superbike from the late 70s.
The lower bracing is done to primarily increase twist resistance and overall stiffness, and is typically designed in for an arm to use especially thin wall rectangular tubing for the main arm.
Drag bikes occasionally use that approach today with extra long custom swingarms on bikes making big power.
George
