@Not_a_ID
Automation and mechanization has knocked out so many of "the human elements" from those "low level" functions, that should those systems fail, we're probably screwed as a knowledge based society.
Let's take this to the logical conclusion and use as The catastrophe, in form of rather mundane economic collapse due to extreme inequality.
Even today large part of the 1% or so of population who provide the others as mass producing farmers operate with razor thin profit margins in an objectively unpredictable environment. While some are getting rich, those mostly do it not by profits of the farming itself, but by successfully averting traps set by bulk traders, as that's where most of the "added value" is. The product's growing cost is often minor part of the end asking price in the consumer market, and producer's earnings is a minuscule amount of that minor part, often only positive because implied long time expenses are neglected (like deforestation, soil salination, etc ecological costs, or even more blatant unpayable deficits in form of credit or subsidies). Curiously we are living in a world where people starve next to overproduced and thus not profitable food.
It is even worse in manufacture if you think about it. The actual production costs are nearly nothing. There's Chinese "toy" clocks for asking price of less than a banana. And that's after that bulky plastic is somehow transported from eastern Asia to northern Europe. Well, to be fair that banana has probably traveled just as much, and equally has most of the price derived from that voyage. But the point is, it's functional electronics in full form that is dirt cheap even after has re-sold at least three times and hauled around the world.
And ubiquitous automation promises to cut those real costs further.
Programmers are long since figured out that despite their work by nature is easily divisible, there's a finite efficiency of doing so. The "social" part of workflow grows exponentially and soon surpasses the real part crashing the overall productivity.
I believe as a society in whole we are way past the point most of our expenses are not the raw resources but esoteric "services" covered by virtual money without any intrinsic value.
I think you all know the story of the carpenter...
...who only wanted to make stools. Simple, sturdy, yet artisan, best stools in the world. He was a simple man and didn't want to deal with trade, so he had to hire a salesman. And they could afford a driver for deliveries. But neither had much understanding of salaries and taxes, so they did need an accountant. Who pointed out they need an marketing specialist. And then a designer. About then they had to replace the old driver, so they hired a human resources manager to do so. And a CEO, to lead all those people. And so on. Long story short, about when they hired lawyer to fight patent infringement, it was indicated by the financial department that profits are predicated to dwindle if costs wouldn't be cut. So they decided to fire the carpenter.
Well, I believe in functional society there's reasons why it couldn't happen globally, because the "carpenter" will move on to start next company. On smaller scale it happens all the time, often with tragic consequences on the individual level.
It's not to say all those 9+ other people besides that carpenter are useless or unnecessary. Of course, the full organization can be ridiculously successful in selling obscenely overpriced stools to people with disposable income, on global scale. The trick is, none of them really need that stool anyway.
However, if enough "carpenters" are fired at too fast a rate, the whole pyramid scheme it is will crash.
Managing to maintain even 18th Century level technology after the fact? That is another matter. Even 30 years ago I'd say enough people had the skills needed for it to be possible. But we're hitting the point where I'm dubious about the under-lying skills being available in sufficient numbers for it to happen now.
Why you want to maintain short living transitional phase?
I think most fail scenarios necessary lead to islands of high tech in a wasteland situation, dark ages complete with wizards and (perhaps mechanical) dragons.
Actually, I do believe it had happened, and the history of (European) antiquity is chronicles of decadence.
Thus there's the debate that the burn out of easily accessible oil may prevent next iteration to ever reach back our level. That may or may not be needlessly pessimistic view, but depends heavily upon how much knowledge is preserved. Note it must not necessarily be in immediately applied form, however the shelf time of any form of storage is finite.
There's a much pressing issue anyway, connected to the same literal food chain. We may as well be way past where we can't actually survive without technology. There's no such thing as wildlife left, only few open air zoo's.
Any "survivalists" who think it is possible to live "from the land" for any length of time are grossly delusional. They should study hydroponic farming instead of hunting, but that's of course not even close that flashy and manly...