For APs backstories mean very little. Usually just a need to incorporate something into your character. The only ones I'd say where I feel a backstory would be useful is campaigns in one location like Kingmaker or Curse because you are in a known location for a long period of time where background items can come up.
For home game a backstory needs to be worked through with a gm to ensure that it suits the world.
As a GM you should make sure to more reward a character for a background more than punish them. If you keep kidnapping their family or screwing them up using their background then they won't submit another one. This isn't to say you can't exploit their backgrounds but you need to balance it with some rewards.