usage of credentialSubject WITHOUT id?

dear CCG,
in chapter "4.4 Credential Subject”, of the Verifiable Credentials Data Model v1.1, I read that "Each object MAY contain an id”.
Can somebody clarify the use-case when the subject does NOT contain an id? As follows?:

{
  "id": "http://example.edu/credentials/3732",
  "type": ["VerifiableCredential", “WeatherCredential"],
  "issuer": "https://example.edu/issuers/565049",
  "issuanceDate": "2010-01-01T00:00:00Z",
  "credentialSubject": {
    “weather": {
      “value": “it rains!"
    }
  },
  "proof": { ... }
}
Is the above (i.e. claims that use impersonal verbs) the only indented use-case for VCs without id in the credentialSubject property?

Or am I completely off track and there is more, or a different idea altogether?

Thank you,
giuseppe

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Giuseppe Tropea
CNIT - Italy
giuseppe.tropea@cnit.it <mailto:giuseppe.tropea@cnit.it>
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