UPDATE: Praveen the alternative you have suggested is not ideal for our customer base. Customers much prefer to be able to activate call forwards via their handset. This is a feature that many customers are familiar with and is a highly requested feature.
If a customer wishes to divert their line manually to an external number, they are unable to do so if the number is attached to an Auto Attendant, Call Queue or Hunt Group.
Customer who have had an on premise system generally use this feature are then disappointed to know that such a feature is not available on Webex.
There are many industries who do not work off a guaranteed schedule every day and require the ability to divert as they please and during emergency situations.