HN is a pretty simple, efficient monolithic web application. Some updates might need a restart. It's OK for some web requests to fail during that time. HN isn't life critical with sixtuple nine uptime requirements.
For stuff like HN, I like the peek behind the scenes it provides. It's all just software written by some humans and way too often people take themselves and their shitty software way too serious.
99.999999 is so overated.