There is a limit to the number of people you can share with. I think the limit is 3, it used to be 5. You also can share anything that isn’t a microtransaction or closed beta. So digitally bought games, dlc, season passes, Preorder bonuses, themes, avatars, ect.
The problem is that the people you share with will have access to certain other things too... like personal information, the ability to delete and change things, and access to your credit/debit card. Which I am not comfortable sharing with people I don’t know.
To gameshare you need their Email and Password.