Understanding purpose of db_ddladmin user in EngageOne Server

Product Feature: EngageOne Server

The db_ddladmin user is required at the time the EngageOne Server database is created.
During the installation of EO Server when executing the database installation script, this SQL user is created with the appropriate administrator access rights in Microsoft SQL Server so it is able to create tables, procedures and views.
In the documentation this user is referred to as ‘eos’. The user becomes redundant and is no longer required after the EO database is set up. It is however recommended not to delete and/or change the permissions of this user in SQL Server.
For the EngageOne Activiti database, it is slightly different. It's structure is not created from any installation script during the installation process, all the database objects (tables, etc) are created once the EngageOne server core bundle is successfully installed and core service is started. So, when the same user is referenced in the for both databases, the db_ddladmin user is used to initiate the structure of EngageOne Activiti database.
UPDATED:  May 24, 2019