Compilers massively outperform humans if the human has to write the entire program in assembly. Even if a human could write a sizable program in assembly, it would be subpar compared to what a compiler would write. This is true.
However, that doesn't mean that looking at the generated asm / even writing some is useless! Just because you can't globally outperform the compiler, doesn't mean you can't do it locally! If you know where the bottleneck is, and make those few functions great, that's a force multiplier for you and your program.
It’s absolutely not useless, I do it often as a way to diagnose various kinds of problems. But it’s extremely rare that a handwritten version actually performs better.
yo, completely off topic, but do you work on a voxel game/engine?
yes and you already know me lol, we have been chatting on discord :P