The forum discussion touches on a genuinely under-documented chapter of aviation history: the decades-long evolution from early area navigation systems to the GPS-based RNAV/RNP infrastructure that defines modern instrument flying. The poster's understanding is largely correct—early RNAV systems in the 1970s and 1980s relied on VOR/DME and DME/DME triangulation computed by onboard flight management or navigation computers, allowing aircraft to fly point-to-point routes independent of the airway structure defined by ground-based VORs. This was revolutionary for airline and business aviation operators flying long domestic routes, but it had real limitations. DME/DME RNAV required adequate ground station coverage and geometry, meaning accuracy and availability degraded in areas with sparse DME infrastructure—exactly the remote, non-towered airports the original poster asks about. Early RNAV approaches were rare outside of trunk routes and major terminal areas because the FAA's approach design criteria, certification standards (like AC 90-45A), and avionics costs made widespread deployment impractical for smaller airports.
The real inflection point came with GPS. Selective Availability was disabled in 2000, and the FAA's WAAS (Wide Area Augmentation System) became operational in 2003, which is when RNAV (GPS) approaches began proliferating rapidly at general aviation and regional airports that had never had any kind of instrument approach, let alone a precision-like one. Before WAAS, GPS overlay approaches existed in the 1990s but were often non-precision with limited vertical guidance. The explosion of LPV (Localizer Performance with Vertical Guidance) approaches in the 2000s and 2010s—now numbering in the thousands—effectively democratized precision-like approach minimums for airports that could never justify an ILS. This is the transition the poster is really asking about: it wasn't a quick decade-long shift but roughly a 20-25 year arc from early DME/DME FMS RNAV in the early 1980s to the mature GPS/WAAS network that exists today, with the steepest growth curve occurring after 2000.
For working pilots, this history matters because it explains a lot about why airspace and approach design still carry legacy quirks. Many older RNAV routes and approach naming conventions, minimum equipment lists, and even TERPS design assumptions trace back to the DME/DME era, and understanding that lineage helps explain anomalies still encountered today—like why certain approaches are annotated "GPS required" versus authorized for DME/DME/IRU updating, or why some legacy RNAV routes in mountainous or remote terrain have odd containment areas. It's also a useful reminder for newer pilots that the ubiquitous, reliable RNAV/GPS approach they fly into a rural strip today is a relatively recent capability, not something that's existed since RNAV's inception—less than 25 years old in its current WAAS-enabled form.
Broadly, this ties into ongoing trends the industry is still navigating: the FAA's Performance-Based Navigation (PBN) NAS Navigation Strategy, which continues to phase out ground-based navaids (VORs) in favor of satellite-based RNAV/RNP, and the push toward RNP AR approaches that allow curved paths and tighter obstacle clearance in challenging terrain. The VOR Minimum Operational Network (MON) program, decommissioning a significant percentage of VORs while retaining GPS backup capability, is essentially the modern continuation of the same transition the original poster is asking about—moving further away from ground-based triangulation toward satellite-derived navigation, with all the same questions about equipage costs, backup redundancy, and how quickly remote or lower-traffic airports benefit from new capability.