If you run dcos_generate_config.sh without a config.yaml, you see this error message:
====> EXECUTING CONFIGURATION GENERATION
No config file found at genconf/config.yaml. See the DC/OS documentation for the available configuration options. You can also use the GUI web installer (--web), which provides a guided configuration and installation for simple deployments.
The GUI web installer was removed in 1.12, so this error message needs to be updated to remove that reference to it.