utter nonsense. small RPM but high torque electromotors are made by making them longer, make a motor axially longer by a factor L, and the torque will multiply

utter nonsense. small RPM but high torque electromotors are made by making them longer, make a motor axially longer by a factor L, and the torque will multiply by L, while the volume also increases by L. suppose we followed your advice and multiplied the diameter by the same factor L to get the same increase in torque, now the volume is multiplied by L squared!