You can go too far with this and become a bender (Not the Futurama robot).

Some stores near me 3 or so years ago would have the backer cards bent...severly....mostly it was done on Star Wars. And truth be told, I didn't buy them. A crease/wear is one thing, the entire corner bent to the state that the cardboard was torn...like buying second hand goods. I do like to keep the backer cards, so damaging packaging affects some collectors, too.