Here's a quote from section 7.2.1 of the rules:
Tiles may not be placed or upgraded in such a fashion as to preclude any Corporation that has not yet operated from creating a legal route using available tiles and upgrades.
Here's the definition of a legal route from section 7.4:
A legal route consists of a continuous unbranched length of track, including a City containing the Corporation's station token (not a Hotel!), not necessarily at the beginning or end of the route.
If the definition of legal route in section 7.4 is correct, every corporation starts with one, so my question is: Why is that quote from 7.2.1 necessary? Is the designer using a different definition of legal route there?