I can understand the reservation about replacing a liner in a car, but in a train yard it's just the opposite. We replace liners all the time on a schedule, and it can greatly extend the life of the engine.
This makes sense for a train, though. The engine blocks are gigantic, so there's lots of "wiggle room" and strength is not an issue. Also, trains put on an incredible number of miles every year, so if the engine block was not designed for easy maintenance you'd have to be changing and rebuilding the whole engine block very frequently, and they are not easy to handle because of their size and weight.
People don't really keep cars that long these days, otherwise someone might have developed a similar setup for car engines. Nowadays if you did that the body would rust away and you'd just have a frame with an engine in it.