Is it me being blind, or are there no folders in /system? I usually put some ringtones in the zip along with deleting some apps etc.... But I don't see a thing inside this specific zip
... did you see the system.new.dat file? This is the image file of system partition that during a flash is used to create the /system... this is the way of CM to supply flashable zip, and the same is also for CM12 official... that's all.