How do you control something that per it's own definition works better the less controlled it is? Hence Le Guin suggesting that the inherent limitless uncontrolled growth goal in capitalism is akin to cancer. Because no cell is better at spreading than a cancer cell and when the body is consumed by cancer, some sort of equality is reached, that being every non cancer cell is equally influenced/wiped out by the cancer spread.
Capitalism can be controlled. Eg in China they permit capitalistic enterprises if it is deemed to "benefit the state or people". They also don't permit private enterprise to run the banking system.
How do you control something that per it's own definition works better the less controlled it is? Hence Le Guin suggesting that the inherent limitless uncontrolled growth goal in capitalism is akin to cancer. Because no cell is better at spreading than a cancer cell and when the body is consumed by cancer, some sort of equality is reached, that being every non cancer cell is equally influenced/wiped out by the cancer spread.