It's not just that. You want businesses to be able to fail if they are being run poorly. That's something that's a lot harder with government agencies, state owned enterprises, and large companies.

government agencies: People rely on them by design. You can't simply shut down the health care or welfare system because it's being run poorly or corruptly.
state owned enterprises: There is pressure from the ruling class to keep even inefficiently run or corrupt SOE going because they provide jobs and patronage.
large companies: They become systemically important. The loss of a single large business can cascade through the economy. See: Lehman Brothers or the big auto companies during the 2008 crash.