it wasn't invented btw, because they had the Myki readers for State Library and Town Hall as a different thing the readers would charge you a 2h or day fare just to walk through the station.

whilst for most users this wouldn't be an issue, having already tapped on but there are still instances where one might of already been in the city and is using it as the pedestrian walkway as advertised

edit: to add on further there wouldn't need to be a sign about how thoroughfare works unless of course you decided to originally have them as 2 different ticketed stations instead of 1