OP's sort of being misleading when they say they "rewrote it in Rust", IMO. They're still using HTML and JS for their UI, rather than a native solution. The size/perf improvements mostly just come from using the OS' native engine instead of bundling Chromium.
As a rust developer, I do too! Those are not representative of rust GUI/3D etc desktop applications. I've made some pretty complicated stuff with 2D and 3D graphics, lots of functionality; expected size is 5-15Mb on Windows, and 10-25Mb on Linux. Less if you don't need 3D.
Funny for sure, but not novel. JWZ also doesn't let his web site linked from HN. Example link (that only works properly when you copy paste, opinionated rejection otherwise): https://www.jwz.org/blog/2024/06/mozillas-original-sin/