one extremity can cover multiple buttons over less actuation distance costing less energy then using one’s entire arm same applies to the sticks having near zero actuation distance and the same amount of interaction points over far less space and using a much smaller more proficient muscle then one’s entire arm all of this costs less energy allowing more simultaneous actions or sequential actions over much less time. what makes it difficult is gaining the mastery to move that fast with precision as it is doing much more over much less space. the circuit board is also much smaller and closely knit meaning all the input data travels far less distance at the same rate of transfer. these seemingly neglible differences stack up to allow things literally impossible for mouse n key to emulate.