#5 Hurt the sport: Caution clock.
In what had to be one of the dumbest moves ever conjured up by NASCAR officials, they decided to insert a 30 minute caution clock into Camping World Truck Series races back in 2016. Although the clock did achieve the goal of bunching up the field and making things a little more competitive, the idea just seemed so unoriginal.
Of course NASCAR seemed to get the idea after a string of successful heat races in The Xfinity Series, but this was probably not the incarnation of the rule that fans wanted. Not only did the caution clock seem completely arbitrary and a stab in the dark that reeked of desperation, it also was critically panned by fans everywhere.
In the end, NASCAR officials deserve some credit for trying something out of the box, especially since it coincided with the Saturday night heat races that the sport was known for back in its glory day, but there are few rule changes as hated as the idea of inserting a clock into racing. In fact, the idea only lasted a year and was then abandoned.