More seriously, I totally get you. I've been looking for how long it would take a few boat in the 11th century to go from Greenland to Canada. By chance, there is historical data about this. But when you try to make up a new world, you start thinking about how everything is related to everything, how are the new clothes made, where you find fuel and other energy resources, what kind of currency is used, how the banks work, what are the politics in place, etc. A simple detail might call for a lot of explanations, and sometimes, it might be best to leave out details that have no direct incidence on the story.
I actually disagree. You know if the year is mentioned, we're going to play around it, start asking questions, try to tweak it to feed our theories, etc.