Starting in the '20s, it became a kind of journalistic parlor trick to crown the national champions in football, a regional sport with limited crossover games. Over the next several decades, those who came up with criteria to figure out the current national champion started to use their criteria to retroactively name champions. Basketball got a similar treatment, which continued even after the national tournaments due to a number of reasons (some teams played in both, some in neither, some in only one or the other). The NCAA tournament consolidated it's hold in the '50s and '60s on crowning a 'true' national champion, but for half the history of the sport there was nothing so clear-cut. Doubly true in football. The Helms was one of the major indexes of this age (recognized as a major selector by the NCAA football title parlance).
Likely UNC made hay of the Helm's to distance itself from State and Duke. It's not on the same level as the NCAA Tourney, but it's not nothing. And when it comes to rivalries sometimes "not nothing" is all the reason you need to celebrate.