Because all modern computer chips and electronic systems (e.g. PCBs) rely on electrical simulation for design and build. Typically, these are SPICE based simula

Because all modern computer chips and electronic systems (e.g. PCBs) rely on electrical simulation for design and build. Typically, these are SPICE based simulators, which are open source and quite old in their methods (you literally set convergence requirements and step times). FPGAs are already digital... meaning that although they (FPGAs) have to be simulated when they are designed, their purpose is digital simulation. Programs are at their heart a discrete digital simplification of the underling electrical operation for the purpose of increasing reliability and allowing greater design complexity.