You weave an interesting fantasy where Galleon chaining is not an exploit, but that non-Euclidean world you conjured up doesn't exist. Therfore, I reject your fanciful logic that "proves" that Galleon chaining is not an exploit. In every player's world view, the cargo of a ship cannot move further than the ship that carties it and Galleon chaining breaks this axiom. Therefore, it is an exploit.
It seems that you missed my point. You are attempting to apply a real-world construct to a game and then say that because, according to your assumptions about certain other real-world constructs the game represents, the game does not match the real world, there must be a bug.
Why can a guy with a club be bigger than a metropolis? It's a game. Certain things have to be represented in a certain way.
But, what you failed to address was to actually pay attention to my proposed alternative perspective, and that is to take away your assumption that a Galleon requires the entire 20 years, 10 years, or 1 year, however long the turn is, to actually travel from point A to point B. As I said, if that's your assumption, you should also be arguing that a unit which moves into a City and boards a Galleon should force the Galleon to be unable to move, since that unit also would have taken the full 20 years, 10 years, or 1 year to move there and just "barely make it aboard" the Galleon by the end of the turn. But, that's not what happens and it's also not what you're arguing for.
What you failed to consider was my point that you could re-examine your assumption that "5 movement points = 20 years/10 years/1 year." Instead, consider thinking of movement points as a different representation. They could represent the maximum distance that a captain is willing to sail his ship until he learns about his new environment. That sailing could actually take as little as 1 or 2 days out of the 20 years/10 years/1 years that the game represents. He might sail back and forth 200 times or even in circles in that time frame. However, at 5 successive points during that turn, his eyeglass scout "looked around" at the nearby squares (aka the revealed squares on the map). For all that we know, for the rest of the 9.99 year, that eyeglass guy could have been running a night club and not even on the boat when it sailed back and forth 200 times. We also know that at the end of that turn, the captain has rebased his new base location to be where the Galleon ends its turn. Those are the only things that we know are represented by the game--the rest, as to what happens in between, is purely up to your imagination.
The game is modeled on parts of real life but it also doesn't necessarily accurately model everything as in real life.
But, what you are doing here is applying your own assumption that "the 5 movement points of the Galleon represents the entire 10 year period that it takes to send the Galleon from point A to point B." I claim that this assumption is your own and is not stated anywhere in the Civilopedia, the instruction book, the code, or anywhere else. As I said, other possibilities exist for explaining what "movement points" actually represent. As long as you hold to your own assertion, you will be unable to open your mind to other possible meanings of movement points. Just because your personal interpretation does not fit well with how the game is modeled does not mean that the code was not designed to work in the way that it works now.
Furthermore, whether or not something is an exploit and whether or not it should be banned must not be based on popular whim or certain players' skill or lack of skill to leverage the exploit.
Why not? I have played a lot of board games with people and those reasons are precisely some of the reasons why we have used "house rules" to alter how we play our games. We play to learn, we play to have fun, we play to release stress, and we play to compete. If some of those aspects are not being met well by a mechanic of a game, then why can't a group of people decide to introduce a house rule that increases the amount of learning, fun, stress-release, and/or competitive spirit? What makes you so uptight about such a possibility that you'd want to prevent it from being possible?
The other problem is this can lead to huge numbers of bans and rules of voluntary compliance; when the number of bans becomes huge, it can become difficult to keep everything straight, play optimally and still avoid all bans which require voluntary compliance (the game will not prevent or warn you that you may be doing something that is currently banned.)
Is that how you think of the rest of us? Unable to agree to a rule and follow it, be it an official rule or more of a "house rule"? Are we really that incapable in your eyes?
When an issue of non-compliance does arise, do you see people as being unable to make a judgment call as whether it was intentionally done? Do you really have so little faith in either the admins or your fellow community members who would likely inadvertently stumble across such non-compliance when reading each others' threads after the game?
If it were possible to patch the exploit away in a new game binary reliably. that would nullify the aversion to voluntary compliance, since the patch would it transform into mandatory compliance.
Okay, we all know that's not going to happen, so why base an argument on something that cannot be? You know the limits of the situation just as well as the rest of us--an absentee Civ 4 development team--so that's what we have to work with and it's up to us to figure out how to make sure that we have an enjoyable competition despite this fact.