I feel like the why is not really needed to be explained, but I will give you the why.
Why this is concerning to me is: Aren't sponsorship dollars tied to how many people are viewing what they are sponsoring. If in 2016 a sponsorship of a Cup car cost (I have no idea, just a guess) $20 million for the year, but I knew that I was going to reach an average of 6 million people per race, then okay cool! Well here we are 6 years later and it's probably still $20 million for the year, maybe higher (again don't know the exact dollar figure) but now instead of 6 million per race, it's closer to 4 million. That's a substantial drop and may impact how much I'd be willing to pay for that same sponsorship going forward.
which is what we've seen in the last 5-7 years. We once saw sponsors like GM Goodwrench, Dupont, UPS, M&M's, Budweiser, Target, Lowes, Hope Depot, Napa, and I could go on and on... sponsor every single race. So those sponsors were on the car every weekend, and investing millions of dollars into the sport, running ads and getting their drivers known by the general public.
What do we have now? We have FedEx, Ally and I think NAPA and that's it... for sponsoring a car each weekend. Otherwise it's a a bunch of 3 or 5 race deals from companies to scrap together the funds to go racing. What this has done (and Denny Hamlin agreed on Dale Jr Download) is not getting these new drivers out into the general public. 20 years ago just about everyone knew who Tony Stewart was, or Jeff Gordon, or Jimmie Johnson, you get the point. Walk into Home Depot today and ask someone if they know who Alex Bowman is, a lot less people would know who that is.
Loss of viewership is and should be concerning for anybody who loves racing. If ratings and viewership increases are good (which they are), I don't understand why when they are down big time for 6 short years ago, it wouldn't be concerning.