Owner of Shared World who is hosting can logout for the day and have someone else who has the world shared with them rehost it while they are offline.There are potential use cases, also listed on the forums as such:

This is a fantastic addition, because it’s a service that with games like Astroneer, or even Minecraft, you have to pay extra for, or even hire external servers to run your shared game on. Any game progress that happens while anyone is hosting a Shared World will be properly restored regardless of who hosts the world next.Only one person can host a Shared World at a time (others will be able to join the current player who is hosting).Shared Worlds can only be played by hosting it as a Multiplayer game.

Any Shared World you own or have been shared with can be copied down as a local Standard World for you to play on your own.Any Standard Worlds from before can be converted to a Shared World via the Save / Load menu.You can have 50 worlds shared with you at any given time.You can own up to three Shared Worlds at any given time.Shared Worlds are stored in the cloud and you can share them with any of your friends so they can host that world while you are not online.

You can now create a Shared World as well as the Standard Worlds you have been doing since Game Preview launch. Listed as a “secret feature”, it’s considered in beta, but was revealed on the official forums as follows: It’s already getting major features, however, like the most recent addition of shared worlds. Hitting “preview program” back in July of 2020, Obsdian’s Grounded has been getting major updates ever since, and is soon to hit full release this September.

Grounded on ps4 download