[bvisness]

To be clear, I also appreciate good reference. But reference is bad to learn from, and frankly a big PDF is not even a very usable reference resource when compared to, say, MDN.

As for lack of familiarity, I am certainly not some grizzled 80s Unix veteran, but if you're comparing the Chrome or Firefox dev tools vs. `perf`, it's no contest. Browser dev tools help devs build an accurate mental model of what their software is doing. It is extraordinarily rare to find command-line tools or other low-level tools that are well designed enough to do this. (Maybe Superluminal now? Tracy?)