Because they really are the same thing like some argue, only not in terms of ideology, but in regards to authoritarianism. That is, the so-called Communism we've seen isn't Communism at all, it's just been another vector for dictators to take over lost dimwits looking for something better than what they are to tethered too. Such was the case with post-feudal Russians just like it was for post-WWI Germans when Hitler entered the picture. Even today real Communism or even Democracy can never work in Russia, they're still given over to their serf mentality. They like being controlled. It's their culture.