I personally consider the ArgoCD UI an anti-feature. Attaching some hulking mass of Javascript dependencies to the thing that has cluster-admin rights to my production cluster is unnecessary attack surface for me.

ArgoCD also has its own auth system and permissions. You give ArgoCD cluster-admin rights, then it uses impersonation to pretend like it has lower permissions. One little bug there and you can trick ArgoCD into escalating your permissions, which happens a lot: https://github.com/argoproj/argo-cd/security/advisories/GHSA...

While not officially supported, you can technically deploy Flux with limited permissions, but ArgoCD's dependence on impersonation means it cannot run with lower permissions.