Like I said, it helps for the instrument flying that they will be evaluating you on. I have friends who are MSFS junkies too, who will sit there for hours flying 747s across the continent or whatever it is that they do. That's not really the point here.
People screw up the sim evals because they can't hold or shoot an approach and get situationally confused.. believe it or not, some people can't even fly straight and level because their scan is lacking. and that's where MSFS comes in, because u can practice all this and then see what your hold or approach looked like.
if you read interview gouges, you will see how some people failed the sim eval portion because they lost situational awareness and screwed up on the approach somehow.. at my first 121 interview, the other guy failed the sim portion cuz his scan was weak. (he hadnt flown in a while and hadnt practiced beforehand.) I mean you could practice in a real airplane with a fellow CFI watching over you.. but why.