I wouldn't categorically say you don't land any aircraft with power on.
Flying a 207 sometimes you would land with full power and back it off as the wheels touched.
In a metro it would be irresponsible to not have some torque applied when the wheels touched down. Usually in the order of 10-15%. If you didn't you would find out about it pretty quick when the props disked up and she fell out of the sky, dislocating your back with the subsequent arrival.
It all depends on the type of wing your machine employs and it's designed wing loading.
A 210 has a beautiful high aspect ratio laminar aerofoil. It wants to fly even when it's standing still. Due to this it typically won't require any power and a cool head would smoothly reduce power before instigating the flare with eyes at the far end of the runway.
However there are times that power may be required. Thermal turbulence, Windshear, aft C of G, hanging off the back of the drag curve etc etc.
All of this comes down to flying the aeroplane in a manner appropriate to the conditions, the weight and the nature of the landing surface.
This is called experience and something you will gain with time.
For now, nail the speed until crossing the threshold, eyes on the end of the runway and use your peripheral vision to judge sink rate, your forward vision to maintain centerline correcting drift with your feet, and raise the nose slowly to place it on the end of the runway.
Enjoy. She is a fun ship to fly and one of the finer singles for a budding commercial pilot to get hold of.
