Not to mention that in a post-apocalyptic scenario, furniture would be plentiful while books would succumb to the elements pretty fast (once the air conditioning turns off).
Also, the amount of energy required to make usable furniture is a fraction of the amount of making paper. Paper can be made from the byproduct of furniture-making but it still requires pressing, drying, and suitable inks require (minor) chemical processing. You can use soot and honey (aka lampblack ink) but it's way more involved than drilling some holes in some wood and then hammering legs into said holes (the simplest form of "furniture").