To be fair, if you do it right then npm should be the only dependency, and then installing all other dependencies (locally) and running the build should be hand

To be fair, if you do it right then npm should be the only dependency, and then installing all other dependencies (locally) and running the build should be handled completely by npm and its scripts. If this is done well then installing and building can be as simple as running two or even one npm commands. There's not really much of a 'figuring out' stage, if you know npm and its common patterns. If the solution to the perceived complexity of the build is to just commit the built artefacts to source control, it's possible that's a warning sign that the build process itself needs to be better organised and simplified, and make better use of the build tools so they help rather than hinder a developer coming to the project for the first time. That's what they're there for.