Actually it is not quite true.

On such rotaryes as Crerget, LeRhone (Oberursel) Bentley - there was throttle (air flow into carburettor) and mixture (fuel flow into carburettor) levers.

BUT there also was Gnome engine, wich had NO carburettor at all, imagine that
It had spray-tube inside air tube, so fuel-air mass mas mixed "as is" and sucked into the engine. Gnome actually had "fixed" position throttle - reostat, which one where setted up to interrup magnetto in the way to 25%-50%-75%-100%, so actually at the position 25% there was only 2x cylinders have ignition on them (i can be incorrect in the number of cylinders - cant remember it at the moment).
The fuel control was only on and off.

Both of types have blip button - ignition interrupter. It was implemented due to high idle RPM`s of rotaryes ~600-700 of 1100-1300 max (~50% of power/thrust) to make easyer such stages as taxing/landing to put lower thrust by ignition interrupt.

Cant say for 100% about how we will make it at the moment, but we will try to;) no promisses