Not that Microsoft Flight Sim or X-Plane aren't awesome and relatively high fidelity simulators, but I don't think that's a feasible QA loop, as a) they're not

Not that Microsoft Flight Sim or X-Plane aren't awesome and relatively high fidelity simulators, but I don't think that's a feasible QA loop, as a) they're not simulating all flight systems on a 1:1 basis, b) even if they did have a fully to spec simulation of the flight control software, it's still insufficient because the real thing runs on specialized hardware, which is not being simulated in flight sims of this tier, and most importantly c) the external environmental inputs are also being simulated so it would be of limited value.