We have used chroots + a bunch of perl scripts for 20 years. Besides APIs for adding/deleting nodes or autoscaling nodes, nothing much changed for us. And, as I have remarked here before (as it is one of my businesses); that extra freedom, esp autoscaling, is almost never needed and, for most companies, far more expensive than just properly setting up a few baremetal machines. Most people here probably vastly underestimate how much transactions a modern server can handle and how cheap this is at a non-cloud provider. Ofcourse, badly written software will wreck your perf and with that nothing can save you.