I don't immediately follow how Rust breaks the ecosystem. Rust has very good C FFI support and fully supports the default C ABI. It just requires unsafe bindings.

In practice, my Python packages broke when they dropped the C crypto support. I'm sure it was theoretically possible to avoid that, but they didn't. And that's ecosystem breakage. (And if the fix is that I the user must go manually install or worse compile extra things, that's definitely ecosystem breakage)