Yes, user privileges can be restricted. In fact, you can create a Group that has certain privileges and then assign the user to a group. That way, you don't have to individually assign the privileges per user. A nice administrative interface that has a detailed user privileges feature is PG Lightning Admin.
Another common approach: You can add views on the tables, allow all the users access to the views, and prohibit access to the underlying tables to most groups. Views are read-only.
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