I personally wish another stock car organization that could compete wish NASCAR would start up. Completion is a good thing, as it forces one side to make changes to improve stuff that's turning fans away.
Once again to use WWE as am example. Back in the early 90s, WWF was doing horrible, fans weren't watching. WCW the other top company at the top come 1996, has a huge storyline and starts completely kicking WWE's ass in the ratings. What does WWE do? It adapts, it changes how it does story telling, and the Monday Night Wars becomes a thing of legend....eventually WCW folds because of mergers (as well as some questionable booking by people who took over with no idea how to book a show) and when WWE was the only real show in town again, it slowly declined. Had a little bit of fight from an upstart in 2002 called TNA, but that eventually started to do poorly. By the mid to late 2010s, WWE was horrible, but if you wanted to watch professional wrestling, it's all you had to watch....until Tony Khan came along with The Elite and started AEW. It got onto TBS, much like WCW was back in the day, and it being a legitimate competition, forced WWE to change up the stuff fans was complaining about, because now fans actually had other viable options. Wrestlers are making more money now because you have someone who can compete with the money WWE has. WWE wants AEW gone, because it's bad for them in their eyes to have competition.
NASCAR doesn't want that competition, because then they know they have to listen to the fans, teams, drivers, etc more often. So they have these tracks agree to not host anything else with stock cars, so nothing can rise up and give them a challenge.
Now this isn't me saying the tracks should be forced to host any other hypothetical stock car racing series. Its me saying NASCAR should not be allowed to prevent it. If another series comes along, then if it scares NASCAR, make changes, improve the stuff fans want to see improved. That's the way you make sure you stay on top, and do it in a fair legal way.