The traditional formulation of quantum field theory—encoded in its very name—is built on the two pillars of locality and unitarity. The standard apparatus of Lagrangians and path integrals allows us to make these two fundamental principles manifest. This approach, however, requires the introduction of a large amount of unphysical redundancy in our description of physical processes. Even for the simplest case of scalar field theories, there is the freedom to perform field redefinitions. Starting with massless particles of spin 1 or higher, we are forced to introduce even larger, gauge redundancies.