Yes of course it is. But I doubt that I'm too far off.
Maiden gigs in every U.S. city have an average of 10,000 people at them (more in Europe and South America). Let's just do the math from the Las Vegas gig, which had capacity of almost 12,000 people, probably had 11,000 tickets sold. I met up or saw people from these message boards, totaling less than 10 people. In Vegas, we went to a bar holding the "Official Maiden Fan Club" meetup and there were probably 150-200 people in there. These are all people actively talking on Maidenfans and the official Maiden message board. Now, let's throw in an extra 300 people just to be on the high end and count things like reddit or even Facebook, that gives us 510 that went to the Vegas show who actively participate in internet discussion with other Maiden fans and probably have a lot of comments about the setlist...and we're still at less than 5% of the people that attended the gig.
Sure this is all made up science, but I really don't think I'm wrong that most people who go to a concert don't care as much about setlists as we do.