The terminology "dark ages" more refers to the loss of Christian leadership than it does of technological or economic loss. Christians love to frame things apocalyptically and that's what's responsible for the common pejorative view of that time period.
A more valid comparison would be the Napoleanic wars, but there too, you can see that really the wars were only possible because economic advancement allowed nations much more resources to devote to war. Europe had to learn how to civilize warfare three times. Each time happened after massive economic advancements.