Saves a control pin at the expense of slightly more code complexity (Woz style!)
I did wonder about that myself - so it's a 2 deep, 8-bit wide shift register. Setting up the address requires writing the hi address byte followed by the lo address byte to the latch ICs. The latch chips copy data on the inputs to the outputs on the rising edge of the CP input signal. Don’t you need two separate control signals to clock different address data into the 74HC574 flip-flops?
