I think this information is not correct. Tere is still auto decay timer of 10 days but it is not shown at the claiming towers... but the claiming towers should decay after 10 days and than your structures will disappear too. Based on PVE server.
2 of my starting sloops sunk in my claimed area because i did not release anchor for 10 days i guess.
You are right that you can get 5k gold with some effort using those very slow sloops... well might be fun for somebody starting the first time into this game... but for all others you want to have a shooner at least... farming that wood, thatch and fibre is not that much of work... like 1-2 hours solo at a good spot. I was lucky to get a gift of 4k gold to add it to my first 1k i made by floatsam and sunken treasures. But sloops are no fun at all.
Just watched a pretty new youtube video harbor run on EU PvP server.... two sloops, two players, 4 cannons and 4 NPCs... shooting on 20 ships about 1 hour... a year ago you would have made a shooner at least and you may survive for 5-10 minutes in such a large harbor. But with gold cost you can't just build that shooner in the lawless next to enemy grid for example.