Those are great questions. The release of ArcGIS Pro 2.5 includes the ability to create a utility network in file geodatabase configuration without the ArcGIS Utility Network extension. The intent of the file geodatabase configuration of the utility network is to enable a single-user environment for prototyping utility network schema, rules, and functionality. It can certainly be used by utilities with a single GIS specialist. The file geodatabase has all the trace, network management and diagram capabilities of an enterprise geodatabase, but it is limited to that single user and cannot be published to the mobile environment or as a map or feature service. The ArcGIS Utility Network is a multi-user environment and was designed for utilities to remove information silos and to increase collaboration between utility business departments such as operations, engineering, planning, and maintenance. The “richest capability” you described come from the ability of utilities to extend the ROI of their expensive engineering data and to provide solutions that optimize the volumes of information used to coordinate and manage their assets, operations, and customers. The utility network leverages many of the opportunities of the ArcGIS Enterprise 10.8 release and was designed to streamline communication and collaboration across your business. With the ArcGIS Enterprise 10.8 and the ArcGIS Utility Network, utilities can publish their assets and facilities across their organization everywhere. The new User Type Extension for the ArcGIS Utility Network enables a more secure method of expanding the capability of their business, provides a safer operating environment, grows their customer base, and delivers a more reliable product to their customers.
