I've made these points before, but I'll try again.
Teams in stick and ball sports don't play every single other team every single week. Stick and ball sports need playoffs because their schedules don't permit everyone to play everyone even a single time. For example, the Super Bowl champion will face at most only 16 of the 31 other teams in the NFL, likely less depending on how the playoff pairings shake out. It has to be assumed that the teams with the best records are capable of beating everyone in their conferences because the schedule doesn't permit it to be actually proven. Even then, the division champions get in regardless of their records, occasionally resulting in teams with .500 records or worse advancing to the playoffs while teams with better records are done for the year.
In NASCAR, everyone plays everyone else every single week. You don't need a playoff because the drivers with the highest points have already demonstrated they're consistently better than the rest.