Just curious why some believe that every AK must have a muzzle device. The same folks would not believe a 7.62x39 SKS or VEPR must have a muzzle device. Same caliber. My money. My Saigas.
Remember that these are all clones, not actual AKMs. Historical 'accuracy' is optional.
The AKs pictured in this thread are clones but if you have enough money to play and in a state that permits Class III weapons, you can have true AK.
Regarding the compensator question. I don't believe that every AK should have a compensator but certainly some do as you mentioned. All the ones I own are correct for the actual military production timeline, be it a muzzle nut or compensator.
The AKM is entirely different than the weapons you mention. The compensator was designed to assist in the control of automatic fire. The device in angled and canted slightly to the right and designed to divert escaping gas from a fired round, assisting the operator in keeping the barrel from climbing upward and to the right. The compensator was probably the only effective measure introduced in production in order to improve the stability of the system during automatic firing.
There were numerous other suggestions; even the most favorable complex combination did not provide an increase of efficiency to the level of the requirements. Despite the adoption by the army, the accuracy was an outstanding open issue. At the end of the 1950s and into the 1960s, design offices, research organizations, and industrial and military ministries looked for ways to improve the accuracy, especially in the framework of the existing structure of an automaton while maintaining its fundamental constructive scheme.
A large volume of fundamental research to verify the influence of multiple factors on accuracy was underway. Specifications of weapons, affecting its stability in automatic mode (the rate of fire, speed, automation, dwell time of moving parts) were reexamined, with several possible solutions that I won’t go into here. Of all the proven interventions the most effective was the use of a small-sized muzzle compensator open type with a compensation pulse of the order of 0.03 kg/s, at an angle of 30 degrees vertically down-right, in the direction opposite to the direction of the angular movement of arms.
Compensators of this type were developed at the Institute of SS Rozanov and at the Izhevsk factory and they provided improved accuracy of fire from a standing position by approximately 2.5 times. After some refinement the muzzle compensator of this type was introduced into production.