Identity has a clear value, both at home and in the workplace. In an organization, every employee and contractor has their own identity. That identity is important to the organization and the individual. In many ways, that identity is tied to their role in the organization. With respect to the technology, identity is tied to what that person can do, what they can see, and what they can edit, etc.
Identity is a necessity in a modern system. It controls authentication, authorization, and privileges. And it also enables you to customize the experience of an application. This is not a new concept - each person has an identity in their email system, payroll system, accounting system, CRM system, etc. A GIS platform is no different.
You would probably never share your work email credentials with anyone. You would probably also not share your active directory login, your Facebook or LinkedIn logins, or any other system that requires you to authenticate with credentials. ArcGIS is no different. A named user account establishes who you are, what you have access to, and what you can or cannot edit.
A named user account also allows you to collaborate with other people. How do you collaborate using a system without identity? You don't. True collaboration requires authentication, and it requires personal identity, and you get all of that with an ArcGIS named user account. Identity is a cornerstone in nearly every collaborative endeavor. The simple truth is that people want to know who they are "collaborating" with. They want to know if they can trust this other person, they want to have context for who that person is, and in many cases, they need to understand the role that other person plays in their work.
Building apps that require no user identity (a.k.a. anonymous use) have in fact been the standard in the GIS world. In many cases, the corporate firewall has acted as the authentication agent. There are great use cases for this model, particularly outside of an organization. The ArcGIS platform's robust sharing and collaboration model supports sharing information inside of your organization as well as sharing information with the public or other agencies.
Each named user license provides an individual with a suite of integrated, foundational apps that enable them to discover, use, make, and share maps on any device, anywhere, anytime. These easy to use apps suit the needs of GIS professionals, executives, knowledge workers, and contractors across the organization. In the past, organizations would develop and support these applications and access to them (identity), or they would contract with a 3rd party to have it done for them. This is a huge value. People no longer have to incur the time and expense of building these applications themselves- the apps are part of the ArcGIS system (and included with the named user license).