the last dark age only happened in europe. most of the world was actually thriving at this time.

You can find "Dark Ages" that have consumed various chunks of the planet, based on when certain central institutions of information collapsed.

Mississippi culture in North America and the Mayan culture in Central America. The collapse of various East Asia dynasties. The sacking of Middle Eastern city states

But we're in a global manufacturing and information economy. If China and the US obliterate critical infrastructure in a war, South Africa doesn't get to pick up on aeronautics or semiconductors or cosmetology where these two juggernauts left off. The info is lost and must be rediscovered.

for a lot of us, the collapse of empire is a light at the end of the tunnel

Nobody benefited when the Library of Alexandria burned.