To mitigate chattiness of ArcGIS Server clusters and notes and have persistent need to check Site configuration, ArcGIS Server and Portal for ArcGIS should use Redis cache or any other memory persistent methods of making both application stateless.
Stateless ArcGIS for Server and Portal will benefit to users when underlying VMs need to resize (scale up) or their number needs to increase (scale out), possible issues can be prevented for end users (like outages, exceptions when not reaching certain configuration performance degradation).
In context of Azure Cloud Services, if AGS or Portal would be deployed in several roles (e.g. worker, web, caching types), those could be fine tuned for any large Enterprise organisation for their particular use on PaaS.
I believe that just delivering generalised VMs of Portal and ArcGIS Server for IaaS deployment is a great start. Getting it working on PaaS is a vision of a much more scalable solution.