What you get out of that being the consequence of disconnection is people being willing to accept a lot more before resorting to that than if the consequences were more mild.
It's the stick for motivating the ugly bags of mostly water.
The 1700s can't keep your electrical grid running let alone replace any of the parts burning out or failing. Anything more than a couple days of it would be at best Flowers For Algernon and more likely suicide for a computer.
Uh, we're talking about the AI getting itself so intertwined into the fabric of industry that the consequences of shutting it off are that society is dropped back to 1700s level.
Yes, regardless of the technology level that the people who do that are left with, one of the consequences of disabling the computer is that the computer is disabled. That's a given.
It's the stick for motivating the ugly bags of mostly water.