Finally I got around to actually researching what I had heard around September 2017. Since then I have have placed 46 books out there and am hopeful that eventually people will begin to enter reviews, or at least little comments of some kind on my bookshelf (http://www.bookcrossing.com/mybookshelf/agilecoachrob).
http://www.bookcrossing.com/about does a pretty good job of explaining what this is all about really. I think one of the most fascinating things that will emerge from this social experiment running since 2001, is the way the membership (http://www.bookcrossing.com/findmembers) will change, and some kinds of insight that will emerge of where and when books are released, and then where, when and how will those books travel to their next release point. Maybe even luckier some kind of "pure" trend about which books are more popular really / unbiased by reviewers, publishers, book sellers, prizes or any other kind of "public persuasion".
Who knows - but I am still hoping that people will pickup one of those 46 and update location/review etc!