The attacks only affect the closest people to them. There is a limit, after which it cuts off and doesn't affect anyone else there.

For example, if there is a knockback or donut aoe, eventually it reaches a max amount of people the aoe can affect in order of proximity.

I took advantage of this when fighting them as a low level blue mage. In order to survive, I simply ran far away because if the hit registered me I would be dead.

This also applies to all of the attacks like Seduced, Forced March and things like that. It cuts off and doesn't apply after a hard limit even though you are standing in the aoe.