lI believe the Nascar downfall began when sponsors started actually measuring their own logo airtime televised during a race, as a yardstick to justify their sponsorship. That corporate measurement did not measure percentage of the TV picture the home viewer saw, but the time a readable corporate logo was broadcast during the race. Those cumulative airtime numbers were drastically increased with cars running in a pack, helped by restrictor plates, and repeated bunching caused by yellow flags that also fitted in the needed network TV commercials.
It's all about the money.
It will not get better.