Information about Log Aggregation in OpenShift 4.1 Documentation

What exactly means the following in the OpenShift 4.1 Documentation:

"The log aggregation solution in OpenShift Container Platform is not installed by default and cannot currently be deployed."

The link that shows that information is the following: https://access.redhat.com/documentation/en-us/openshift_container_platform/4.1/html/machine_management/creating-infrastructure-machinesets#infrastructure-moving-logging_creating-infrastructure-machinesets