Twitter's failwhale-heavy Ruby experience is a good example. Ruby and especially Rails are good examples of trading hardware for programmer convenience. This is absolutely great when you're banging out an in-house app for 100 people, and there's no problem spending $1 per user-month on hardware. But Twitter's revenue is only $0.60 per user-month, and they need to spend on things besides severs. There is a reason that they needed to switch away from Ruby to a much more complicated architecture: https://blog.twitter.com/engineering/en_us/topics/infrastruc...

I also saw some people go the other direction. They had a Java app for serving a high-volume website. But the developers had a rewrite itch, and the execs were afraid they couldn't get acquired without a more hip technology stack. They even hired a fancy consulting firm to help, but when the first version was ready to go it was incredibly slow. Like two orders of magnitude slower to render a page. The rendering times were considered normal in Rails-land, but were a real problem at volume. So they spent another 6 weeks putting in a lot of caching while the ops people ordered a bunch more hardware.