The problem is that when the software works well, it's hard to attribute it to all the experience of the developer whose knowledge of what performance traps to

The problem is that when the software works well, it's hard to attribute it to all the experience of the developer whose knowledge of what performance traps to avoid has helped the software. It is only when performance problem shows up that people actually notice things and measure things since it's worth measuring at that point. But there is still value to the experience based optimization steps developers use based on their prior experience with imilar software without any measurement (with the caveat that it doesn't complicate the software or make it hard to understand).