As one brought up with a love of maps, both old and modern, I wonder how projects like this ever draw breath.
Armchair experts who have only ever built a Hornby OO gauge layout, something with Lego or at a push assembled a garden shed. From there they deduce that "it can't be that difficult", add on as you've alluded to, a romanticism with old railway lines (many of which closed before their proponents first drew breath) together with a - delete as applicable - deluded / unrealistic / over-optimistic view of how the world works and why the old adage of "build it and they will come" really isn't the basis on which to build a railway line and I think you can see how such things come about. Add in the fact that computers and the internet mean that any clown can put together some pretty powerpoint slides, take some photos, do a bit of photoshopping and put it on a website and make it look vaguely reputable. Go back to the 1980s and these guys were stuck with a 'John Bull printing set' (that they'd been given for Christmas) and could only produce a few leaflets which they'd have to advertise in a small ad and rely on somebody sending them a 'stamped addressed envelope' (remember those ?) for distribution.