Think of the live demo as end to end integration tests. I'm essentially running them manually on stage. It's much easier for me to make unit tests work vs fully automated, end to end deployments, backed by real infrastructure, networking, and security.
Many of my open source contributions, libraries, and tools that I host on GitHub were created while working on a live demo. It takes a lot of work to make things look simple in front of thousands of people.
The other by-product of live demos is end to end documentation such as the Vault on Kubernetes tutorial. I had to create a new automation tool, vault-init github.com/kelseyhightowe…, just to improve the UX of such a complex deployment. github.com/kelseyhightowe…
Here's another example. I was working on a live demo for a Go meetup, and in order to make it look simple, I first had to contribute HTTP basic authentication support to the Go standard library -- with plenty of unit tests. github.com/golang/go/comm…
Great live demos also serve as a teaching tool. Live demos often help people see the big picture, and understand how everything fits together, in a way that's difficult to replicate with unit tests and documentation.
