Is db root password in config file necessary?

According to https://github.com/mozilla/common-voice/blob/main/CONTRIBUTING.md
a minimum config.json file must have following

{
    "IMPORT_SENTENCES": false,
    "MYSQLUSER": <root_username_here>,
    "MYSQLPASS": <root_password_here>,
    "DB_ROOT_USER": <root_username_here>,
    "DB_ROOT_PASS": <root_password_here>,
    "MYSQLDBNAME": "voice",
    "MYSQLHOST": "127.0.0.1",
    "MYSQLPORT": 3306
  }

Why do we need DB_ROOT_USER & DB_ROOT_PASSWORD? We have already allotted mysqldbname and given full privilege to mysqluser.
Revealing the rootuser & password would expose entire mysql server instance to CV app. Is there any specific reason that we need to mention root when we have already created mysql-user?