The NEC allows the switch to be grounded when using metal screws attached to a grounded metal box. The requirement to remove the plastic washers holding the screws, using switches with self grounding clips or using a bonding jumper are simply not in the NEC when the switch is attached to a box that is metallic and grounded.
I know what the section you quoted says - it does not specifically address the situation of the OP where the metal box is recessed (assuming less than 1/4 inch) and the switch yoke is not seated tight to the box. What is your opinion on that situation? Before NEC required yoke to be grounded in all installs I say don't worry about it with non metallic plate, now I usually connect an EGC just in case inspector does not think it is sufficient although if the screws are tight against the yoke I really feel it is bonded well enough, but that is just my personal opinion.