Because there is many ways to approach design, starting from a flat surface and fold it give sometimes interesting result!
At Edita Materia the structure of this chair is made out of one piece of bended plywood that is split at the end in order to maintain the back of the chair.
At Made in Ratio where it takes one hour to bend one layer of plywood
At Tokyo design this chair come out like a folded paper
At Daa the bended metal contrast with the softness of the chair