simple, rust is still the cool kid in the block. and some projects written in it are really worth checking out.

Rust is very popular and its ecosystem is still developing. Performance is on par with C while the codebase is easier to maintain, so replacements for other programs written in Rust are often popular.

Although I would say that the programming language a project is written in is generally useful information, so it's other languages not being mentioned enough, not Rust being mentioned too often.

marketing

Well, maybe it should be done more often for other languages. There's many a software project announced on HN that I click thru to, on account of its promising title, only to find out it's written in a language / ecosystem that makes the entire thing less appealing to me. So I think it's good practice, actually.