It's not true that no consensus is needed for a document just because it's
not a WG product. Anything that comes through the IETF stream (including
AD-sponsored documents) need to reflect consensus.
That's generally true the vast majority of the time, though there are
exceptions for some Experimental or Informational documents, which is
why the flag is there in the first place.
We do occasionally produce documents that describe proprietary
protocols or that republish outside documents in the IETF stream. We
try to do those in the Independent stream instead, but it's not always
the best or right thing. When they're published in the IETF stream,
the point is that we have consensus to publish them, but we might not
have consensus on the protocol that's described. In those cases,
we'll use "No" for the "Consensus" flag.
Barry