Stalin's paranoia did cause a huge mass of Red Army Deaths. The 'Purge' ring any bells? Hundreds of fine officers were cut from the ranks, killed or shipped to gulags. This created an atmosphere of fear, where the comissars watched and approved every single move.
Winter War is a great example. Any Finn will give you the bleak comparison between the modern Red Army and the post WW2 Finns, who were armed with rifles, a few Bofor anti-tanks, and short term weapondry. The Red Army had TANKS, Airplanes, and artillery galore. It's a great example in the north, where a Russian commander could push through, and hold the Finns in place for the entire span of the war. Most Red Army commanders were cautious, hoping to funel their thousands of troops along patchy roads through the forests. If they were smart, they would blitz through the south, in the middle, applying overwhelming force and the shock of tanks to break any Finn defenses. They didn't, and this resulted in thousands of Red Army deaths.
The only reason why Stalin didn't use a nuke was because of MAD. That was the greatest invention of man, MAD.
If Hitler had a nuke, then he would use it regardless.
However, had Hitler been in control, his steady amount of killings would have resulted in mass revolt and his overthrow.
Stalin's paranoia caused a state of fear across the globe, and resulted in many of the problems of today. Civil Wars between US backed Democratic parties, and Soviet backed Red parties. Stalin is evil because his long-term effects have a negative, more far reaching problems, that has resulted in more havoc and destruction than a great anti-Hitler force that held by only threads. Hitler was short-term. Stalin was long term.