I am an AMG, so I have no visa issues. The trend I have noticed is that for the most part there are a bunch of us not getting the same interviews at both top tier and middle tier programs.
Actually, what you have pointed out is more reminiscent of a reporting bias.. i think people who are posting regularly on this thread ( not me) are doing this to vent, help others etc etc. So I would not base your conclusion based on this.
However, what you have mentioned has been a lingering thought in my head for the last few days now.. But there is nothing we can do about it,can we?? I guess if there is a red flag somewhere, sometimes it may inadvertantly be mentioned during interview.