How can agencies running 10-50+ WordPress sites get reliable infrastructure without becoming hosting experts?

https://spark-wiki.win/index.php/Why_centralizing_plugin_management_stops_constant_firefighting_and_cuts_admin_overhead

Which specific questions will I answer and why they matter to agency owners and ops managers? Running dozens of client WordPress sites brings predictable headaches: uptime incidents, plugin conflicts, slow builds, client billing disputes,