It's an inferior technology.

The double doors have to seal together in the center, there's a flap (called an articulating mullion) that swings when you close the door and creates the seal between the doors from the inside of the fridge.

But there are two problems: the force of swinging the flap stops the door's path and blocks it from closing if it's misaligned at all (or the seal is misaligned, or loose, or cheap), and it's attached to one door making one side easier to close than the other.

It makes for a more finicky design.

You can improve the reliability of your fridge closing by organizing the items you pull out the most to the side without the mullion attached.