You can't compare OAuth with SAML. OAuth is authorization and comes only ever after authentication, which is OIDC.
But to respond to your critic: It is good that apps let you know that you are IN FACT not merely logging into something, but grant that app access to your Google Drive. This is a very important information! Imagine your mom signs into ClashOfClangs (a malicious clone) and the IdP would in fact NOT tell your mom that the app will have access to all her files because it may be confusing
But to respond to your critic: It is good that apps let you know that you are IN FACT not merely logging into something, but grant that app access to your Google Drive. This is a very important information! Imagine your mom signs into ClashOfClangs (a malicious clone) and the IdP would in fact NOT tell your mom that the app will have access to all her files because it may be confusing