It does not really matter for the Low Technology website of course, but if you get into a serious car accident and the surgeon is like "sorry but our solar powered operating theater is down right now, that's just life sometimes" that would be a very unwelcome thing to hear.
If we focus the same resources on providing reliability where it is needed most, we could actually improve reliability of outcomes. That is, for the same cost of providing a few hours of battery backup for the entire grid we could provide weeks of battery backup for hospitals and data centers.
Suppose twitter/reddit/HN shut down for 10 hours a day.
10 hours was just an arbitrary number, but there are plenty of more creative solutions. Shut down every March, or Weekday mornings, or every other hour.
That's up to the customer to decide. Insofar as we live in a world where customers decide the fate of businesses in a do or die way, I feel the conclusion is obvious. Either the customer shares your philosophy that your downtime is part of an enjoyable rhythm of life, or you die.
That's why guaranteed overnight delivery generally costs more than waiting a week or two for your package.
I work at a company that provides business services, and some customers are fine dealing with irregular availability of resources if it means the service cost an order of magnitude less.
It's not common in power yet, but in the future a hospital might pay $1/kWh for high-uptime power whereas someone else might pay $0.01/kWh for excess capacity provided as available to charge their car.
If there are any issues with the grocery store or the technologies in it, then perhaps it's possible to pay in cash. If there are larger problems with the grocery store's supply chain, i can just go outside to my greenhouse and get some fresh veggies. If i don't have a greenhouse, i have a bunch of beans and other canned goods in my cellar, as well as crackers and so on. If i don't have my cellar, i have a bunch of frozen meat in the fridge. If i don't have said meat, i have a rifle and a forest with animals for that. And if i don't have any of that, i can always just go to my neighbours and ask whether they have anything to share (or offer the same sort of help, should they be dealing with the same hypothetical situation, instead of me; things would only break down when everyone would be starving).
If there are electricity interruptions, i have a few UPSes in place. If the UPSes run out of power, then i have a diesel generator in the cellar (with the appropriate ventilation system in place). If i don't have any diesel, my house has a stove that burns wood and has central heating with radiators, as well as candles or a petroleum lamp, or even a flashlight with a generator for lights. And if HN isn't online, i'll just read a book, since there is a shelf with some lovely literature to be enjoyed, or will simply write something in my diary, as people do.
I'm saying this not to discredit the fact that many people choose to live in the larger cities, since there are definitely different advantages to that choice, however at the same time you have to consider the overall trends in society, when you take things as electricity or a stable food supply for granted, which may not always be the case.
That said, there are relatively few things that are truly time sensitive, such as having a supply of important life sustaining medication. I wouldn't expect my grocery store to have a 99.99% uptime, nor would i expect that even out of my electricity supply, hence the UPSes and generator, and HN going down wouldn't be the end of the world either.
And when we are talking about the greater supply chains that we don't see in our daily lives, honestly there always should be a business continuity plan in place - if your computer system goes down because of Y2K, a solar flare or the data center burning down, then you should be able to keep on trucking with calculators and some paper. Anything less is not all that responsible, if we're really talking about important domains.