Most industries are not bursty. Overprovision in not expensive for most businesses. You can handle 30000+ updates a second on a 15$ VPS.

A multi node system tends to be less reliable and more failure points than a single box system. Failures rarely happen in isolation.

You can do zero downtime deployment with a single machine if you need to.

> A multi node system tends to be less reliable and more failure points than a single box system. Failures rarely happen in isolation.

Just like a lot of problems exists between keyboard and chair, a lot of problems exist between service A and service B.

The zero downtime deployment for my PHP site consisted of symlinking from one directory to another.