The answer is in the legislation
As you quote S216 says “may”. That denotes that its not compulsory
To answer the second part of yur question. The secretary is just the post office correspondence goes through. They would refer a mediation request to the committee for a decision.
What I believe the legislation is aiming to promote is for owners corporation to sort out their internal differences in house. Thats never easy when there are opposing views.
I think the internal mediation is a good idea, but in the wrong place. You see these processes in larger firms who hav resources to draw up a process and then usually to engage independent arbiters.
Thats probably not going to happen in strata, so we use NCAT to solve all the internal problems.