Title has it: I see more and more roads (especially the stone kind) that are build in a way that following them is impossible - but they work for teleportations.
My suggestion is that the 'travel' option should check the exact path the character would take when actually following the road, which would lead to 'travel' working exactly as good (or bad) as 'follow' - removing the exploit of creating a road that can only be traveled and denying access to the milestone(s).