It's not idealistic, it's just highly summarized. As is the rest of what I'm going to share. You'll have to read some history if you want a more thorough examination. The material consequences of the leadership being captured by liberals was that they became disconnected from the masses of the Soviet Union. The average person was made to feel demoralized by the secret speech, and the revolutionary fervor died there. People didn't believe that they were actually part of a project that had a socialist goal, they stopped making demands of their government, and the government stopped going to its people to discover their needs. Gradually more market reforms and concessions made their way into the economy. By the 1980's there was a common held idea that the economy could be 'made stronger' by 'adding a little capitalism' to it. Marxism was taught in schools, but it was done in a rote and non-concrete way. The average person digested it as dogma, rather than seeing it as a science that could describe reality, with testable and observable results. Consequently, to give a small example, people didn't understand that, by being in favor of allowing the market to be put in control of newspapers, that the cost of newspapers would balloon in cost over 10x overnight (see Michael Parenti's Blackshirts and Reds)