RDS MySQL "validate-password" setting in the parameter group questions?

I am trying to change the "validate-password" setting in the parameter group, by creating a new parameter group and editing the parameter validate-password=ON. After rebooting the instance and changing the parameter group the parameter validate-password=ON does not work. The same procedure when tried using command line from the following link : https://aws.amazon.com/premiumsupport/knowledge-center/rds-mysql-validate-password-plugin/ works? So my question is what is the purpose of the "validate-password" setting in the parameter group then?