I would certainly agree that looking at real history greatly assists with perspective. Here in the UK we used our steam trains into the 1960s. The main reason for that was because we had a sizeable coal mining industry on which the country was economically reliant. Conversely there was at least one area in the US that banned them around the 1930s, due to concerns about pollution.
It's funny, the only folks I ever hear talk about the "Diesel era" are Dieselpunks. It isn't (to my knowledge) an officially recognised historical term. Partly I suspect because the decades they're referring to, weren't always as wholly Diesel powered as some of 'em seem to think. The nature of Diesel fuel meant that it was originally used to power larger engines. Smaller vehicles such as motorbikes, cars, tanks and other things that tend to excite us, all actually ran on petrol initially. What they're really enthusing about is the "Machine Age", but introducing Machinepunk now would likely only result in further complications.
