To limit the probability that seats will be dislodged or moved or be unstable, which could lead to persons tripping over or falling over or off the seats, which could lead to harm to persons.
To limit the probability that seats will be dislodged or moved or that there will be insufficient space along the rows of seats to move easily to aisles while persons are evacuating or moving to a safe place in an emergency situation, which could lead to delays in the evacuation or movement of persons to a safe place, which could lead to harm to persons.