Arc Milestones and Ship's Departments?

I am curious after looking through the arc milestones and the errata it appears that there is no way to raise the Ship’s Department Rating to 5 as the arc milestone caps it at 4. Is this an error as a character can at least become the best of the best in their discipline with an arc milestone?

I would be interested in knowing why if this isn’t an error or I missed something why a ship and its department crew couldn’t obtain the acknowledgement of being the best of the best in the fleet for their department.

Wow, you’re right! I tend to think that’s a typo as well.