@sweetsandman
It's not "forcing" anything, however you said it yourself "3). It would encourage crews to spend gold... having the full assortment of supply crates from the merchant would become increasingly important.
So while not "forcing" players to buy crates, this would be, by your own admission, a shift in the meta to make buying crates basically necessary to be competitive against other crews. That is something I am not in favor of.
Also, if supplies are "everywhere" and refilling is "relatively easy, even in the midst of battle" then what exactly is the point of putting a cap on supplies? You're saying that there are too many supplies that people have which make fights too long I guess, and the solution is to cap the amount of supplies, but also it doesn't matter because resupplying even in battle is super easy anyway? If that is the case, why make the change at all?
Also, 200 cannonballs is a decent amount, but as a solo sloop you can put 200 cannonballs into a gally no problem and they keep going, because the can...wait for it... repair! There is no reason to handicap the sloop against larger vessels by adding a cap, especially a smaller cap than the other ships. Adding a cap just creates an arbitrary penalty for no good reason. If you do the Skeleton Fleet you can easily go through 100+ cannonballs, and then if another ship attacks you're just SOL because of a random supply cap?
I just don't see a good reason for this at all.