For fiction and chatting, no. For eyewitness accounts or providing evidence, yes, provenance matters. Also, a famous name (or at least, one well-known to you)

For fiction and chatting, no. For eyewitness accounts or providing evidence, yes, provenance matters. Also, a famous name (or at least, one well-known to you) has a lot of embedded trust associated with it that was earned elsewhere, which is why impersonation matters.