Another ship sinks me. Instead of just getting my supplies and any loot I had, they also get to ransack and destroy the fort my friends and I spent time building up? Imagine a new or casual player doing a treasury or shrine, their ship gets sunk without them knowing it, and now their fort (and anything in it placed by other members) is destroyed too. Sounds like they'll love this idea.
If I sink a ship and get access to their fort, can I still do so even if they log out? If not, how is that fair to me?
You never mentioned how any of the supplies are to be procured. If I'm in an HG fight and need say, 50 wraithballs, would I or my opponent be able to do this?
I have screenshots of the amount of supplies my friends and I often have at the end of our sessions. I'm talking hundreds of cannonballs, a lot of meat, pineapples, over 100 chains, a number of curses, etc. imagine how it'll look at the end of the month if we're able to store it all. With the amount the game has to "remember" for so many player forts doing this, and considering how we already have issues with ping, fps, lag, stuttering, disconnects, etc., what affect will this have on current performance? At the end of the month, we'd have so many supplies, it would be gamebreaking and not fair for newer/smaller forts, or new/casual players.
Then you have the classic example taken from a page from World of Warcraft--that one guild member who waits til 3am, ransacks the place, and /gquits. How would you like Rare to deal with such players who do this (on top of the amount of tickets they already receive on a daily basis)?
Speaking for myself here, I'm not the kind of player that just logs in and stands around doing nothing. I want to get busy, be active, have amazing battles with awesome players, meet new players who become friends, work on rep, comms, etc. I'm in a call on discord with my crew, and we've got plans made from the start, we log on and go. We don't have to log on and stand around with 23 others waiting to set sail with others just standing there. Discord eliminates the need for that aspect, saving time, money, and resources on development of this.
These are just some of the items I thought of right away after reading your post.