This always assumes these applications are built by competent people who value efficiency. The job market is full of people that think they need high scalabilit

This always assumes these applications are built by competent people who value efficiency. The job market is full of people that think they need high scalability but then underestimate the cost of an HTTP request or the memory footprint of keeping an entire dataset in memory. It has happened several times in my career building platforms that I have to double check that packet capture I just took from that single Kubernetes node is accurate (my favorite is 22k DNS queries, all A IN s3.amazonaws.com, in a 0.2s span). Similar things happen with memory and CPU.