Comment by andersmurphy

I'd argue the opposite vertical scaling us a whole lot more effective than horizontal scaling if your using a language that has both real threads and green/virtual threads (go or anything on the JVM). You get such insane bang for your buck these days even over provisioning is cheap. Hell direct NVME can easily give 10-100x vs the crappy network drives AWS provides.

Zero downtime deploys have been solved for single machines. But, even then I'd argue most businesses can have an hour of downtime a month. I mean that's the same reliability as AWS these days.

Really, there are a handful of cases where you need multiple servers:

- You're network limited (basically you're a CDN).

- You are drive limited you need to get data off dirves faster than their bandwidth.

- Some legal requirement.

This is before we get into how trivial it is to shard sqlite by region or customer company. You can even shard sqlite on the same machine if you need higher write throughput.