A different way to put it would be that it is based in the way that U.S. law allows you to sue anyone for any "damages," real or imaginary, only proving that you got hurt. Any potential employee can have an idea that is derived from trade secrets or other material not meant for people outside of an organization, and it's not possible to simply turn off this ability or create a distinction between ideas that are completely independent from that information or not. Because of this, it's possible to incur some level of damage to an employer with an idea that was technically had at any time of day.
