OIDC is basically a protocol, and is what you're describing. It's _the_ attempt to standardize on a common set of scopes, discovery mechanisms, etc for making it easier to build apps that use OAuth2.
And the platforms that do support OIDC properly just require a login portal URL to integrate support for it.
Want to add Microsoft logins with an oidc library? One url.
Want to add Twitter / Facebook signin? Go get an OAuth library and write several hundred LOCs to detail the scopes and crap you want form them because they are non-standard.
Forgive me if I'm mistaken, but isn't OIDC for authentication/profile information? Does it include standards for things like accessing contact lists, reading/writing files, sending email, etc?
A bit late: you're correct, but it does provide a standard API for looking up additional metadata, even if it's non-standard. That's using custom claims and/or the user info endpoint (which can include custom claims). You can use custom scopes to limit what is available as well.
