It's ok because we're still paying for it. QoS degradation is worth it. No need to have 99.999% then you can have 90.84% and still people to pay for it.

It does have a worse downtime record than my tiny VPS that has a recurrent packet routing problem and keeps going offline. Measurably so.

Scale changes the math. Your uptime chart would look like a crime scene too if a million people were pushing random crap at your server all day and every tiny hiccup could land on an open PR or a hot write path you forgot about. GitHub looks like old code glued to ancient VMs that people are scared to touch, so a small outage can drag into a wierdly long one.