Hehe. You came from a different direction. My main point is that reading, thinking and contributing in Swift is more familiar with the majority of developers. Currently.

Swift usage is largely isolated to Apple's ecosystem, which doesn't have a ton of overlap with the open-source ecosystem.

I agree that the usage is isolated and it is not represented in the FOSS community. And I am not an advocate for doing so. Though it is compatible and if it is a possible alternative it can be considered. If you compare it to other Syntax it is reading very easily and you can pick it up in 20 Minutes. They could even require to explicilty use type annotations to further aid accessibility for possible contributors or audits.

... creating libraries which can be called from virtually any other language, like you can with C and C++. Which means you're not locked into the Rust/Apple/whatever ecosystem ...

Let's agree that a lock-in should not be dependend on the implementation language. There are other implications on the build which may arise. I am neither familiar with rust nor Swift. Comparing implications for building and linking can't be compared by me on a professional level.

I further - without research - call out that Rust comes with implications on either library implementation or linkable procedures for an author in order to link to it. Neglecting thinks like nested interop between host/implementation language here.

But even if Rust was the most overhyped garbage, it would still be garbage that people are familiar with. ¯\_(ツ)_/¯

Two things: Every developer I have met in person whishes to get some project in Rust. No one has seriously started pushing or even learned it thoroughly. Second point: I didn't called it garbage! The language as it is awesome. I don't like its readability and its packaging.

When I read Rust sources it isn't fluent in my inner mind. Sure it is due to familiarity but I would also argue that the over-expressiveness kills reading speed as well. Though that should be inspected by more objective and competent people though.