Honestly I'm just a dumb web dev and even though many of our performance problems can be solved by horizontal scaling, there are a minority of cases where latency is important and that's when things get really fun :-) No more downloading random halfbaked libraries off the web, architecture starts to matter, vm settings start to matter, gateways/load balancers in the middle start to matter, even code optimization starts to matter again just like in good old days.