Interestingly, ISO standard documents are sold for a non-insignificant price and DRMed, while people writing them are volunteers and/or paid by their employers to participate in standardization committees. A company willing to build equipment for an industry running on ISO/IEC communication protocols (like electric power distribution) may have to pay thousands for relevant standards, or rely on someone's interpretation of said standards to implement the protocol before they even begin, not considering certification costs.
This is a very funny thing to assert on a forum that's entirely delivered via openly standardized (via IETF, W3C, etc.) technologies!
(Also, you certainly can monetize an RFC. In fact, that's the norm in a lot of RFC categories: the various PKCS-derived RFCs are a direct extension of various patented standards that RSA[1] sold software atop of.)