The problem is that NDHQ (the centre of the universe) assumes everyone does everything the same same way. When an Army unit deploys, every member of that that unit (the ones that are going that is) is individually attach posted to the deployment location/operation. Ships, on the other hand are simply assigned and there is no real requirement to attach post anyone because nothing actually changes. Ships are self-contained in that they take everything with them (files, admin office, pay office, etc). Even their mailing address doesn't change. In a previous life, everytime NDHQ published rules for a new benefit, I had to call and remind them that unless they really wanted to deny the benefit to deployed ships, they had to adjust the wording to include those other than whom were "attach posted" to an operation.
No, the problem is that the navy thinks in terms of ships and not in terms of people.
There is a requirement to track where
people are, not just ships. Attach posting a person to a ship means the official records state that "Pusser was aboard HMCS Retentive from 15 July through 18 September 2007" - so ten years from now when it's discovered that HMCS Retentive was, in fact, infested with cooties, we can track down Pusser and ensure he gets his shots.
Right now, if I understand CountDC, the problem is that many sailors are brought aboard to fill empty billets but their pers files are never properly annotated - so once the HMCS Retentive cooties scare comes up, "the system" shows that Pusser was at his desk in Jonquiere as N1-5-7-12 at that time and he may not receive the medical attention he requires.
Associating benefits with attach-posted status is a different issue.
(And the current CF method of attach-posting to a deployed UIC has other, more interesting impacts, since the "units" never deploy - meaning a true pedant would observe that CinC commendations can't be given, since the unit that forms the core of the battle group never deployed - its personnel did, but the unit itself did not... but that's another discussion better suited for a stand-up table in the mess)