The computing power required to run a simulator is immense. The sheer number of mathematical calculations that have to be carried out whenever I move the yoke in the sim is incredible. This is a level of computing that your flight simulator on your desktop PC could not handle. Try going to a full motion sim and instead of flying it ask to see the computers that run the bugger!
So many variables are involved in flying through the air that you really do need that level of computing to simulate it fairly accurately - even the dynamics in the full motion sims used to train us aren't 100% bang on. I doubt your plane you mention is "90-something % realistic" since such a level of simulation would require more than one desktop PC.
Ok gocha, thanks. I quote what they say though:
"The PMDG 737NGX features an unprecedented level of systems fidelity. Developed over three years with technical input from Boeing and a team of real-life 737NG crew and maintenance advisors, we have painstakingly modeled nearly every system on the real aircraft in a fully dynamic and realistic manner."
PMDG Simulations
But if it does indeed require a lot of computing power to run something like that then maybe you're right
