For quite a while, a dedicated module has supported the SAML protocol to realize SSO / Authentication via external ID Providers. In recent years, the more lightweight and flexible OpenID Connect protocol gained momentum, providing means to employ OAuth 2 mechanisms for the same purpose. Furthermore, it allows not only authentication via interactive usage but also non-interactive use, e.g., for connecting programmatically and realizing automated remote control.
OAuth 2 has become a reasonably widespread standard for providing identity within enterprises and beyond their borders to all applications, especially in general mobile applications and banking and government markets.
Support of OpenID would therefore widen the market to connect to customers' ID Providers and unify authentication concerning other systems.
Note: This feature is a long-standing and often requested extension to the capabilities of FirstSpirit, registered under ID CORE-13167 with Crownpeak.