One could, for instance, run “static” sites with the data stored in a SQLite database. Update on write apps often can do okay with 90% uptime. It’s the “generate everything in every request” crowd that needs an HA solution and why do we keep doing this to ourselves?

Yes, static generation is a great way to go if that works for your use case. Throw it up on a CDN and you'll likely have five 9s of uptime. I don't think that's a viable solution for a lot of applications though.

Half of arguments on the Internet are someone trying to win an argument they lost elsewhere. If I could get some people I work with to actually run the numbers on how much it costs us to make everything dynamic, versus how much we earn versus static, I think we’d quickly arrive at an agreement that most of it should be static with a little AJAX thrown in for the 10% that needs to be special.