In other words, MSFS is the same, just different. And the only places it’s different are data resolution, complexity, coefficients, and performance and handling to the extent that one shouldn’t expect to learn much about aircraft handling from it. Additionally, it’s not “validated” by anybody. OK. I think that’s probably a bit generous, but, in general, I agree with that. They are the same with those differences. The space shuttle and an RC model airplane are the same – just with some differences.
The
method is the same, but the depth and complexity of the simulation is very different of course.
Some people seem to think sims like X-Plane are inherently more realistic because shape determines aerodynamic characteristics. This simulation method is actually no more likely to produce a better result than the data table model. The difference in performance is almost certainly due to the more complex aero model and equations of motion used in X-Plane. MSFS is highly simplified.
You certainly couldn't replace the FFS with MSFS. However some pilots use MSFS plus complex add-on for practise. An airline could use such a desktop trainer in their training programme, would receive no credits for it, but might get better training transfer in the CPT, FBS and FFS sessions.