I'm not sure I have ever seen a benchmark on HN that wasn't called misleading and useless in the comments.
But I agree it is hard to get benchmarks right -- I'm not even sure there is a 'right', as a benchmark will usually be based on certain assumptions that only sometimes apply. (Unless you are benchmarking your own actual production code, in which case you know it's assumptions are valid -- for your own code).
So I don't think that's a reason not to share benchmarks. But I _do_ think it's a reason to be really transparent about exactly how the benchmarks were done. Ideally all code should be available on github.
Then people can examine your assumptions (including ones you knew you were making and ones you didn't) and modelling, as well as fork or pull request to do benchmarks in some other way to better model the scenarios they care about.
Although also in my experience, you get LOTS of people telling you your benchmark is wrong because of X, Y or Z -- sometimes they are correct that it doesn't accurately capture something they are interested in, sometimes they are just confused -- but virtually nobody actually interested in writing code via fork or pull request to capture what they are interested in. Once you put out a benchmark, everyone in the peanut gallery thinks they are entitled to keep demanding you change it in various ways for them.)
No matter how much time you spend on it and thought you put into it, publishing a benchmark on HN is probably the easiest way to have lots of people telling you you're an idiot who did things wrong. It almost seems like HN collectively wants to discourage people from running benchmarks -- or from sharing what they found publicly.
But it's because doing good benchmarking is so hard -- well, that's exactly we need more people working on it, and sharing how they did it so others can improve upon it, etc, right?