My problem with the NFL Overtime

The rule has always been that if the team that first posesses the ball scores X points, they win ... and the other team's offense is SOL.

Prior to 2012, X > 0.
In 2012 they raised X to 6, making it much harder for OT to end on the first possession.

If there comes a day when enough teams are marching down the field and scoring touchdowns on the first possession, then they might change the rules again.