Why isn't recommended to use CertGen in a production environment?

If I generate new CertGenCA.der and CertGenCAKey.derfiles I don't see a problem using gencert for production.

This is for the communication between Manages servers and AdminServer.

What is the reason of this recommendation?

The doc states:

The CertGen utility generates certificates that should only be used for demonstration or testing purposes, not in a production environment.

As of version 12.1.2 of WebLogic Server, the CertGen utility generates certificates with the following attributes by default:

• 2048-bit public key.
• SHA256 message digest algorithm.
• Subject Key Identifier extension.
• Authority Key Identifier extension (if the CA certificate contains a Subject Key ID.)