I share your conclusion that "the perfect cross-platform library" does not exist, and I also agree that we could use Rust to make one that's worse than the Rust

I share your conclusion that "the perfect cross-platform library" does not exist, and I also agree that we could use Rust to make one that's worse than the Rust standard library, and we could use Go to make one that's better than the Go standard library. However, Go's limitations make it hard to make one that is much better than the Go standard library. And the Rust standard library is so carefully designed, that there's really no need to go ahead and redo the work. Unless you need something it explicitly doesn't support (and doesn't promise to support!), in which case there's a wealth of crates at your disposal, which also benefit from a rich type system and strict compiler checks to ensure correctness at compile-time. People don't just switch to Rust and write code like they did before. It's different enough that it makes everyone rethink how they approach a problem. But it doesn't just get in your way - not only are the compile errors excellent (and the core team is working tirelessly to improve them even further), it gives you the tools to build solutions you'd never pull off in other systems languages.