> Imagine all the plastic items in the World suddenly as susceptible to rot as wood. It would fundamentally change almost every aspect our existence, in a very short amount of time.

Hardly. Some usages of plastic would need to be altered, but most would be fine. The conditions in which wood will rot are very specific (the forest floor, basically) and reasonably easy to avoid, surely something similar will be true for rotting plastic. Pre plastics, practically anything, including all kinds of liquids, was stored in wooden barrels.