Swift is an Applications programming language first, digging its way down to the system.

Rust on the other hand tries to be a system programming language, but with no success at that. And it's not a popular Applications programming language because there's no support from any major software platform vendor.

Swift doesn't have a runtime, a linked library isn't a runtime, if you think it is, then you don't have the qualifications to discuss this.

It is not a problem to store one 50meg file on my 32GB iPhone or 128GB server, it would be in a 32KB microcontroller, but nobody is trying to ship Swift as a language for those.