What is the benefit of doing this?

All users with Write access to Cases on their profile are able to see all Cases ownedby Community Members

Community users in the same community can see each other, regardless of the organization-wide defaults.

Portal users in the same customer or partner portal account can see each other, regardless of the organization-wide defaults.

Community Managers are able to view all Community Users regardless of the organization-wide defaults

Limited information on Community user profiles are publicly accessible e.g. Name, Photo, Reputation Level, Description