You can actually see it if you know where to look - edges of big cities but it is most visible in the countryside and smaller towns.
And if you want to see how real Armageddon looks like, go visit Yubari: https://en.wikipedia.org/wiki/Y%C5%ABbari,_Hokkaido
The collapse was due to local coal mining no longer being viable, but it still demonstrates how it looks like when a city goes from 107000 people in 1960 to 5600 in 2025.
Large empty areas where homes and factories used to be, old billboards for stuff that no longer exists, whole school buildings and gymnasiums out of use and overgrown. Most shops closed or hardly open & few remaining occupied buildings in the middle of it.
Was a really special experience & the local coal mining museum was super interesting - just wondering for how long it can continue going...
Seems somewhat better than Detroit.
The question really is - how does an abandoned town hurt us? Sure, there may be some sympathy and loss for "what once was" (same as the pictures of the abandoned classrooms in Prypiat).
The US has had similar things happen but the spread out population has given it some resiliency (many towns that "collapsed" when the mill/factory/whatever shut down continue in a strange afterlife as a suburb of a nearby city).