
I am not sure where the OP got the idea that there is a resume writing association in existence.
Resume writing is just a part of the services offered by an independent writer who is trying to expand beyond academic writing.
This is a form of writing that is different in many ways from academic writing and can easily be completed by anyone who has a computer.
People don't usually require resume writing since Windows Word has several templates available for anyone to use for that purpose.
However, there is a need to proofread a resume and edit it, depending upon the job requirements of the Human Resources Department.
Resume writing does not require writing in as much as it requires formatting and presentation polishing.
So writers are not directly involved in the creation of a resume or resume writing, but are directly involved in resume formatting.