AFAIK, all Mercedes engines are self bleeding. Certainly 123,124,210 and. 201 cars are in my experience. When I hear about some of the nutty procedures employed, from hanging the front of the car on a hook to pressure filling, my assumption is that either the car has a clogged radiator or the owner has a brain fart. Your procedure works fine, as long as you are sure to run the heater.

Cars are out there which have air bleeds, and require special fill procedures. For example, Porsche 944, Jaguar XJS, Corvettes with reverse flow cooling, probably more. So check rhe FSM if you are unfamiliar with the vehicle.