Regarding a statement given in my 'Electrical Machines' textbook about synchronous machines?
Well, you cannot deny there is a force between rotor and stator. It's exactly the same force between two fixed permanent magnets. They are fixed but if let loose would collide with each other. This can't happen in a motor because the rotor is constrained radially. Does torque also exist? Yes it does - to overcome windage and friction exhibited by the rotor. That's the no load scenario and clearly an increase in torque exists when mechanical load is applied.

It's also interesting to note that if the rotor was mechanically lossless, the rotating mag field would be physically coincident with the exact centre of the rotor pole aligned with it. As load is applied there becomes a misalignment that inevitably produces a hight force between rotor and rotating field. Maybe this is a more satisfactory explanation?