Of course, but we are not arguing about the point of the article, I'm contesting the exact claim that "WebAssembly is almost always faster than JavaScript". Admittedly, not because it's such a big mistake on the author's part, but because I'm a bit irate with the usual flow of discussions about WebAssembly here on HN that take this claim for granted and regurgitate it incessantly. This is not the case for the mentioned reasons: data copying overhead and JS itself being compiled by JIT resulting in pretty performant code if well-optimized. Also, the comparison to JS only makes sense when we are talking about running both in the JS engine, not against a dedicated WASM runtime, otherwise it would be tantamount to arguing that Java is not faster than JS.
By the way, if someone really wants to dig into the issue I recommend an article from one of the V8 authors where he dissects one such WASN success story: https://mrale.ph/blog/2018/02/03/maybe-you-dont-need-rust-to...