You can also check out Differences in the SAS 9 and SAS Viya 3.1 Platforms document at the Viya documentation site. Much of the information in this doc is pertinent to a SAS administrator. It does not specifically take the tack of "What are the advantages of SAS Viya from an administrator's perspective," but you can extrapolate some of the reasons like:
industry-standard installation/configuration tools
integration with corporate LDAPs for user and group identity information
resilience of worker nodes, insulating server processes and jobs from crashed nodes
reduction in the number of servers to monitor/manage
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