>>Bookbinders used parchment to strengthen their book bindings; that material was expensive and therefore people often chose to cut up old, medieval manuscripts.
Parchment, made from sheep, goat or calf hides, is very expensive and labor intensive to make. The cost of labor of a scribe to write a page of manuscript book is not large compared with the cost of the page of parchment. Hence there is really no need for a printing press while using parchment.
The printing press was enabled by two other developments in the prior 3 centuries. One development was mechanization of processes like the pounding of retted flax to extract linen fibers to spin linen thread and weave linen cloth. The other was mechanization of pounding linen rags to extract fibers to be used to make linen paper. Both windmills and waterwheels were used to power these processes, and the price of linen paper decreased greatly. It became widely used for government and business documents as the price fell.
Thus, it eventually became economic to do printing.
It really took off after a century of the Black Death and the fall of Constantinople. Instead of relying on the consensus of the village elders (all or most of whom died in the plague) better secular recordkeeping became necessary, which meant a more general literacy, which drove demand for writing materials. The fall of Constantinople cut off access to higher end trade with southern and eastern Asia, led to European circumnavigation of Africa, and the European exploration and diaspora. Good idea to add palimpsest to the keywords, thanks!