We have become accustomed to the conventional login scheme where users need to enter the username and password to access the program. For decades, the approach has been dominant even with the possibilities of these days to login with social media or even face ID.
If an app requires stronger protection, certificates, hardware tokens, etc. are implemented by administrators but not all users assume this is the most comfortable authentication method.
For most instances, the authentication method involves web browsers. Browsers work like bridges on desktop and mobile platforms linking access information and applications. In this case, changes to the authentication flow require the support of the browser. Since harmony is one of guiding web principles, several parties are needed to make changes to the platform. W3C WebAuthn Working Group was targeted at this, at the creation of an interoperable specification which all parties could implement.
In other words, the standard specifies an API that allows the development and use by web apps of powerful, attributed, scoped, public key-based credentials for strongly authenticating users.