One of the challenges with amateur radio is finding a repeater that works where you are, where you were, and where you're going.
In the state of Colorado, RepeaterBook lists over 200 repeaters on 70cm alone. This makes for a lot of work when selecting a repeater to use. Does the repeater have adequate coverage in my area? Is it open? Is it still up? The information on some repeaters hasn't been updated in years.
Suppose you're traveling in multiple vehicles to a remote location. How do you coordinate communications along the way? Will your pre-selected repeater even work when you get there? The antenna may be on top of a mountain, but is it pointing the right way? One particularly high site in Colorado has multiple repeaters on it, but some face the plains and some face the continental divide.
With a properly designed DPCN system, these are no longer concerns. The radios are programmed to roam to the site with the strongest signal. All the sites are networked, so if part of your group falls behind or gets too far ahead, you will still be able to maintain contact. You can select a talkgroup that won't disturb other system users.
If you're out of range of the sytem, there are always simplex channels for local communications. And although DPCN radios are usually limited to a single band, they work very well on legacy/analog repeaters, frequently outperforming the ham-specific models.
DPCN system technicians generate drive reports, which use computer software, GPS, and digital radios to log coordinates and real-world signal strength of actual system repeaters. These reports are combined into an actual map of system coverage, not a theoretical map that is calculated based on potentially erroneous information.
Obviously this works well for established DPCN systems. New systems need more help. If there's an area where you'd like to see coverage, let the local system administrators know. With enough interest they may be able to cover your area. Of course, if you have the inclination, you are always welcome to join the local team and build it yourself! There's no substitute for learning by doing.