>>1936685It's simpler than a coax. Kamov chose that for maneuverability.
>>1936188The setup actually has better lift, and more stable in hover.
>>1935427The tail rotor solution was cheaper to mass produce, so that won military contracts, got more engineering experience and became standard. So now only outlier specialist helis use alternative rotor arrangement, like the Chinook heavy transports and Kaman lifters.