I used to spend hours on flightsim doing all sorts of wild things for fun, and when I first went to fly a real aircraft, the instructors all thought that I had many hours experience. Although theory was never my strong point, flightsim can improve hand-eye coordination, instrument scan and the precise small movements needed when flying a precise approach, or the fast reactions when flying during a bad day.
I also knew all about navaids and how to read them as soon as I first flew IFR. It gave me that little bit of a head start that was useful.
I agree that there are loads of nutters out there that think they can do it all, but MSFS is not a bad tool if you are aware that it's only a game.