The alternative to recycling newspaper and cardboard is chopping down forests and turning them into pulp, a process that also needs a lot more logistics, chemicals, energy, and of course forests that you have to re-plant.
Recycling newspaper is a no-brainer from a cost perspective. You can't recycle forever though, each time you lose some wood fibers that are too short and have to be removed from the recycled pulp, so you have to add fresh pulp.