The submission title would beg to differ.

(I know, it explicitly calls out "benchmarks" as the context.)

I think languages like Rust or Swift have significant advantages around safety over C/C++, while not sacrificing much in terms of performance. But if one language's benchmark contributors are willing to put in more effort than another's to eke out additional performance, then you're going to see skewed results in favor of whichever has the more fervent evangelists or whichever language has more to prove.

If the goal is to compare performance of two languages which can express the same optimization in exactly the same way, and only one uses it, then the benchmarks fail in that respect.