What Really Happened After Stalin in the USSR for Revisionism to Happen?

I'm not well versed in Soviet history, so excuse and fix my misinformed takes in the text.

One of my friends claimed that Stalin's purging of the revolutionary cadres like Trotsky, Zinoviev, Bukharin, and Kamenev because of the ideological differences caused revisionists like Beria and Khrushchev to rise to power.

As I said earlier, I don't know much about Soviet history. But didn't those revolutionary cadres try to dismantle the USSR because they thought it betrayed the revolution? Also, I know Beria is a rather controversial figure, and the "Death of Stalin" movie didn't help much. What really happened during and after Stalin's term to cause the USSR to fall into revisionism?

It's not that related, but there's also a famous Kyrgyz writer, Chinghiz Aitmatov, who supported Khrushchev because he claimed the Stalin era was brutal. Iirc, there was a teacher in his book "The Day Lasts More Than a Hundred Years" who got bullied by the village for not killing himself when he got captured by the Nazis during WWII. He later got arrested for reasons I don't remember. I believe Aitmatov's books might also help with the anti-Stalinist opinions in my country.