Flamegraph is literally just a perl script that visualizes the stack traces collected by perf/dtrace (kernel). It's a good tool though but it doesn't need to be oversold for its capabilities, the hard work is done by the kernel. And honestly, many times it is not that useful at all and can be quite misleading, and not because of the bug in the tool but because how CPUs are inherently designed to work.
What concept in particular? There is nothing novel about that tool, it visualizes the stats collected by perf, and as I said it's not even that useful in root cause analysis in performance regressions, which is like the main point it is marketed for.
