Why? Because sadism lies at the heart of communism. Communism is just the excuse.
Communists are thieves, that take what you've earned and keep it for themselves or to buy influence they can use to steal more.
Jesus told about thieves:
"The thief cometh not, but forexcept to steal, and to kill, and to destroy:Communist (and Moslem) thieves hate the Lord Jesus Christ and the spirit-born children of His Father of whom He is the Master, not Marx (or Allah).
I am come that they might have life, and that they might have it more abundantly."
(John 10:10 AV)