There are few reason why one should use CDN (Content Delivery Network)
rather than managing multiple data centers. A CDN works towards faster and reliable delivery of content to the end users based on the system that data centers of CDN providers are spread at different geographical locations, and if a request is made by user the CDN automatically detects the location and deliver content from the data center nearest from the end user.
On the other hand, managing multiple, globally located data centers
are extremely expensive and resource exhaustive as well. Setting up multiple data center would require huge front costs and even more would need for operating expenses. Additionally, it requires months to build, set up and deploy a completely functional network of data centers. But in case of CDN, deployment process is easy and quick and more importantly it does not require huge capital expense.