I think you are overselling the killing aspect although its true.

The reason is that strict Marxist don't believe that entrepreneurs are producing any value. If anything, they are believed to produce negative value i.e. surplus value is an appropriation of value from workers. If you get rid of them, the negative value disappears and society is better off.

Since only workers produce value (labor theory of value aka LTV), they can only produce what is already confirmed to be valuable. Reproducing the work of other workers doesn't violate the labor theory of value, but producing something that has the potential to be worthless does. [0]

You can see that a disdain for intellectual property law and an obsession to only produce what others have already produced makes cloning a natural strategy for communism.

[0] The mudpie criticism against the LTV is usually rebutted by communists saying they would never produce something worthless. It is implied that they have efficient central planners tell them what to produce.