That's kind of a rude thing to say, suggesting that compilers aren't real programmers. Nevertheless, it is the case that most optimizations in the compiler are motivated by real issues with somebody's code, as opposed to compiler engineers thinking up optimizations in their heads.
> by writing kernels... his use-case is much more practical than anything that compiler designers could imagine.
States that compiler designers cannot even imagine the practicalities needed to write kernels. Which is quite a blanket statement to try to make and defend.
