Sea of Theives would end up very shallow without the threat of having your progress challenged. There are games like Deep Rock Galactic that cater for this. In SoT there are also ways to minimize getting griefed. Don’t put up an emissary flag. Don’t hold treasure. Doing the original tall tales gives you an instance where pvp is turned off. If you seek treasure, be ready to defend it. I don’t think the game should focus on the once a month players too much.
I don’t buy it. Indoor type people look way younger than their outdoor peer group in their 40s and 50s