That is true but another variable in this is advertising... all those shooters, even some of the worse ones had somewhat decent advertising.

I had no idea the game existed if it weren't for the fact that I got really bored and browsed through game demos one day. I also found a trailer for a game called Demon's Souls that day both were great finds that I would have not known about until they were off the primary market. (I now check sites like this every day to make sure I don't let any gems slip by me again!)