A key point of this article is exactly that Swift abstractions aren't nearly as "high level" as they could be. That "ABI-resilience by default at dylib boundaries" choice, while understandable, is also quite costly in terms of added complexity to the language and implementation. We already saw this happen to a different extent with C++; I think that Rust developers just saw the writing on the wall and that's why they ultimately chose to stick with a very C-like approach, where the user needs to deal with all ABI-resilience concerns herself.