For some people the missing OpenID Connect may be a feature. But it provides some sort of vendor lock-in. A lot of components can easily be attached via OIDC and i would not use an authentication provider/middleware without OIDC support.
Yes, OIDC is quite important for the central identity hub, especially when you get beyond custom apps. If you are building an app, Supertokens with their SDKs and APIs might be a great choice.
As soon as you start wanting to integrate with other COTS or OSS applications (a forum, help desk software, slack/teams), you'll need OIDC (or perhaps SAML, depending on the age of the software) support.