The last real collapse which ended civilization was the end of the bronze age.
The end of the Roman Empire was way more transistory in comparison.
Yes, civilization was set back, yes, rulers changed, but if you scrap the whole renaissance/ enlightentment propaganda about the "dark ages" there were more things that survived than collapsed.
In the end we're living in the same civilization as Aristotle, Augustus Caesar, Charlemagne, Elizabeth I., and Bismarck.
Let's hope global warming / nuclear war doesn't take care of that.
Complexity and the chaos caused by complexity are certainly factors that cause disasters and require damage control. It also provides renegades more opportunities to disrupt normal operations when law fails to serve the public rather the plutocratic elite.
But this doesn't mean theres a direct causal relationship between complexity and societal failure.
Think of Isla Nublar and the cloned dinosaurs that were able to reproduce, migrate off the island and survive outside containment despite the systems that were emplaced to prevent them from doing so.
Pop history only starts caring about societies as soon as they get big and complex, and so you only hear about the "collapse" of complex societies. While complexity might be a factor in collapse, it is one of many, and the narrative that complexity causes collapse is often used by grifters, usually with some idea of having to return to "a simpeler time", without "degeneracy and (((bureaucracy)))" etc.
I keep hearing about this Oppenheimer movie, and it just makes me want to hear Alan Oppenheimer say "I am become death! Destroyer of worlds!" in his Skeletor voice.