That's what worries me. They might not have. If I were interviewing in Washington or at another school, then that would be the case. They would have had to have liked something else about my application enough that were willing to overlook what they did. However, this is not true if they just give an interview to anyone who meets the minimum requirements and has a complete application, which they might very well be doing in Alaska, Wyoming, etc. If there was no meaningful vetting of your application beforehand, in which someone said "gee, even though this is bad, it's been awhile and this applicant seems to have turned things around, and everything else looks solid, and we really like this over here...let's give them an interview invite." Then yeah, you might be facing a meaningless interview situation, because they would never accept someone like you no matter what.
I guess there's no way of knowing, but it would be nice to be able to go into the interview knowing that something is actually on the line, because someone saw something in your application that made them think you were worthy and someone they could see themselves accepting. That's not the case if 90 people get an interview out of every 100 who apply.