Historically the benchmarks have been crafted in a way to make them seem faster than their real-world and well-formed opponents (e.g. the io_uring vs epoll benchmark). One issue that was pointed out was that the io_uring benchmark eschewed proper error handling in order to avoid some branches, whereas the epoll benchmark properly error checked. This reduced the benchmark times considerably, though no correction was ever published after the fact.

This is why in the Github issue I mentioned in another comment there are some people understandably a bit annoyed. I don't choose to jump to conclusions about Axboe's intent, and my original comment wasn't meant to do so.