I work on Argo. Those instructions are mainly for demo purposes because many of the examples need admin privileges. The amount of access which is needed, is really dependent on what your workflow is doing (e.g. if your workflow needs to deploy a resource, then you need to give the service account 'create' privileges on that resource). Currently, the bare minimum for a workflow to function is outlined here:

https://github.com/argoproj/argo/issues/983#issuecomment-435...

I will make sure that the docs are updated, so that this information is well understood.