This is actually incorrect in the case of MSFS. If you are going on popularity, look at the actual data:
Also on actual hours flown the small group of us that are able to share data using our Hours & Hobbs application are showing similar results to the top 10 at the moment. Of course the 320s and others are up there but they are by no means at the top.
You must be watching a different YouTube to the rest of us.