There should be rubber hose between any two major components that may move independently. If the tank is not mounted to the same frame that the tubing is mounted to, then rubber is needed. Rubber hose is used between the frame mounted tubing and the motor mounted fuel pump. It is also used to be able to remove certain items like gas tanks, filters and carb.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn