When you login as kubeadmin in the argocd UI using SSO, you can create applications, so you don't have read only access.

The first sentence of 

https://docs.openshift.com/container-platform/4.13/cicd/gitops/configuring-argo-cd-rbac.html

states:

"By default, if you are logged into Argo CD using RHSSO, you are a read-only user."

What we think it is not accurate, and it should be changed to something like:

"By default, if you are logged into Argo CD using RHSSO, unless you are kubeadmin user, you are a read-only user."

4.13