Reads to me like a slightly more general way of saying "this is not the time to specify an API in Rust that you intend to maintain in perfect backward compatibi

Reads to me like a slightly more general way of saying "this is not the time to specify an API in Rust that you intend to maintain in perfect backward compatibility forever". But if they said that directly they would be inviting a wave of counter-arguments that they most likely already went through themselves, repeatedly, considering how much love Rust is getting for in-tree use (where APIs can be refactored at will). I believe that their main issue is that they don't want to end up with the Rust equivalent of a Java API stuck with Vector and Enumeration.