Companies are making use of dark fiber on a large scale mainly for the cost savings. If your organization has a lot of data, you need to move around or if you have nothing to do. paying thousands or thousands of dollars a month to a Century Link or a Comcast or some other Internet provider.
Most important benefit of using dark fiber for some organizations is the fact that they can provide physical redundancy for their existing systems. Enterprises often find that if they are using two different providers as part of their disaster recovery, business continuity plans, both providers may rely on some of the same physical infrastructure. So in the case of a natural disaster or something as simple as a construction accident or burst water main, they may lose both their primary connectivity and their backup at the same time.
Another benefit or using dark fiber is the potential speed. Whenever an organization is using commercial Internet service, traffic gets bounced around different points before arriving at its destination. But with dark fiber, organizations can get a straight line from point A to point B, which improves performance.