NASCAR's ascendancy to the pinnacle of American sport and subsequent fall from grace is much more complex than rule changes and team fluidity. The NASCAR phenomenon is largely attributed to the following:
1. Changing of the Guard: Today's drivers look more like a metrosexual boy band members and accountants compared to the characters of yonder. Back then NASCAR had personalities as big the engines with colorful names to match like Rusty Wallace, Dale Earnhardt, Dick Trickle, Dick Passwater, Jim Bob Cornhole, Bob Pisshard, and Anus McFlappin III. These guys were larger than life and put asses in the infield. No one is lining up to Kevin Har-whatever and Danny Ham-and-cheese on white.
2. NASCAR's popularity in the late 80s to mid 90s largely coincided with the golden era of mustaches and mullets. When high fashion and sport collide, you've got lightning in a bottle. Think zubaz and football or halter tops and soccer. After the fad dies the sport tends to follow.
3. Shorter Attention Spans: With our instant gratification, over stimulated, smart phone carrying, ADHD culture where kids can't sit still for 10 seconds let alone a 5 hour race, its a miracle that Americans figured out that people driving cars around to the left isn't really a sport but they DID! They really did. NASCAR is just asinine and despite all the demands on our collective attention, people actually thought about it long enough to figure it out. Remarkable.
In conclusion, the rise and fall of NASCAR has happened.