I had the same question, honestly. But it might have some benefits...
A cargo ship has a top speed of under 25MPH (20 knots). A Class 5 freight train can hit 80 MPH and there's no *technical* reason why they couldn't go even faster. Even with the increase in distance by taking the long way around, you can maybe reduce transit time. Such trains could also load and unload deep inland, closer to where the cargo is needed, eliminating multiple handling steps.
I still don't think it's a *good* idea, but it's slightly less crazy than it might initially sound.