When I was a young man, I worked at a restaurant, and the lights went off.

I being the hero I was, wanted to keep the show running, bought some candles, ovens worked fine, water worked fine (for now). I wanted to charge cash. But eventually big boss came and shut us down since light wasn't coming.

And he was right, cooking and working under those conditions is dangerous for the staff, but also for the clients, without light you cannot see the food, cannot inspect its state, whether stale, with visible fungi, etc...

Yes, the perfect worker would still operate under those conditions, but we are not perfect, and admitting that we only can provide 2 or 3 nines, and recognizing where we are in that 0.01% moment, is what keeps us from actually failing so catastrophically that we undo all of the progress and benefits that the last bit of availability would have allowed us.