I agree, I think there is often a faulty assumption by many developers doing benchmarking that their underlying environment doesn't matter. Often I see performance results posted with little mention of the details of the environment. At least here they posted they were using a high-end SSD, but note they just say they're on a "Dell XPS 13", as if there aren't multiple variants of that model produced every year for the last 5 or 6 years.

You're probably also right their multiple test runs resulted in the OS caching data, and a lot of the test runs may have just been testing in-memory performance instead of raw storage I/O performance.