In addition to the point made in the article, even some RFCs do not indicate "what the IETF thinks". And I'm not just talking about April 1st RFCs.
The IETF has the "Independent Submission Editor" stream of RFCs, which produces RFCs without getting IETF consensus. These RFCs are considered to be work "outside" of the IETF, but can still be published as an RFC.
The mechanism described in this document does not have IETF consensus
and is not a standard. It is a widely deployed approach that has
turned out to be useful and is presented here so that server and
browser implementations can have a common understanding of how it
operates.
The IETF has the "Independent Submission Editor" stream of RFCs, which produces RFCs without getting IETF consensus. These RFCs are considered to be work "outside" of the IETF, but can still be published as an RFC.
A recent example is https://tools.ietf.org/html/rfc8674 from Mark Nottingham: