Agreed. No one cares. In the universe of frequent seamen sins, failure to post an MMC is below trivial.
That’s how I see it. Is there a requirement to post and do you need to post are two different questions. The answer to the first is evidently yes, the answer to the second is it depends.
If the CG comes aboard and says they are going to hold the ship until the MMCs are posted then if you want to sail you need to post them.
I’ve not yet had anything like that happen.