LCC's don't overbook because they fly routes which are not susceptible to the type of passenger who no shows. If you were to look at the overbooking profile for BA or any other full service carrier on say London to Amsterdam I think you would find that they only overbook to a very small number because the passenger historic profile on the route is that they will turn up for the flight.
On routes to Africa and South America the overbooking profile is much higher because the historic passenger profile is that large numbers will be unable to travel on the flight they have booked for many reasons. There aren't any locos on these routes so the argument about locos not overbooking is specious at best, and cantankerous at worst.