Strictly speaking, it hasn't even been the norm in AMERICAN history and, in the scheme of things, is a relatively recent development. It seems to me that periods of stability are always as memorable as they are brief, while periods of chaos and upheaval are forgettable and hard to classify historically which is why multiple different unstable situations all with different causes in different places at different times are collectively referred to as "the dark ages."
Actually, the 'dark ages' are so called because of a paucity of archaeological or historical data. The term was originally used to describe the strata found in archaeological excavations between the Roman and Medieval periods, where there was very little pottery to be found.
Roman and Medieval sites can often be dated to within a decade or two based on the potsherds that are found there. But the entire second half of the first millennium CE is almost entirely devoid of such evidence, and so was known to pottery experts as the 'dark age'; and that terminology spread to other archaeologists and to historians.
The term 'dark ages' has now fallen out of favour with archaeologists, as new archaeological techniques are detecting the previously undetectable traces of the wood and leather goods used in that era. Obviously these organic materials don't survive as well when buried, in comparison to pottery.
