The idea that there was no "fall" and that late antiquity is just a "transition" between arbitrary value-balanced political org charts is what's not supported by the evidence. This revisionist take is annoyingly common these days -- see https://www.amazon.com/Fall-Rome-End-Civilization/dp/0192807... for a masterful refutation and defense of the original interpretation. If you look at industrial output, lead pollution levels, sophistication of literary output, literacy rates, and tons of other metrics, you'll see a dramatic decline around the time that the Roman social order fell apart. Britain became nearly illiterate. Italy was ransacked by the Gothic Wars and its population collapsed. The aqueducts stopped working. The Pantheon was half-buried (the front doors couldn't be opened for centuries) and full of muck. It was, altogether, an absolutely miserable period of history. Gibbon's history of the era is masterful.