This cl tool can be installed as a devDependency. But they say to install it as a dependency if you are in a monorepo.
Why is that?
devDependencies in the root package.json can be used in all packages in the monorepo. This is generally used to co-locate test-related deps and config (jest, eslint, etc).
A couple caveats:
devDependencies. If you need to run a CLI from a child package, that CLI needs to be in that package's devDependencies. (transpiling, flowcopy, etc)
dependenciesfor a given child package still need to be listed in that child's package.json. (obvious, perhaps? just clarifying)