Why is Group Policy needed?
As computers have become more sophisticated, managing them and the users that use them has also become more challenging. Consider the types of users that used computers twenty years ago: there was only one type - PC users. Today administrators must deliver and maintain customized desktop configurations for many types of workers like mobile users, application workers, database users or developers or even for those with specialized operations like data entry.
Consider Security. This used to be confined only to login and password operations, but it must now be more critically managed. Security problems used to be limited to viruses, and introducing virus protection software usually took care of the problem. Not anymore. Problems like identity theft, hacking, online file theft plus the myriad of spam and new virus offering make security a top priority. So security settings, including updates, permissions, and firewalls, are some features must be delivered efficiently to all the computers and devices in the organization.
Change and configuration management is now the order of the day. New users must hit the ground running; they must be productive quickly without costly training. And if there is a computer breakdown or disaster, service must be restored quickly without or limited data loss or time lost. Furthermore, if there is a breakdown, the recovery should be at minimal cost. These considerations force administrators to set policies to implement change quickly and which therefore will affect large numbers of users and computers.
These are reasons why Group policy is needed. One policy for the group.