[gpm]

Perl 5 introduced forwards incompatible changes less than a year ago. Perl 6 was so backwards incompatible that after 20 years of work they renamed the language to something else - it last had forwards incompatible changes sometime in january.

Not only are these not meaningfully better, they're also the opposite of what I would hold out as a "successful versioning model".

Rustc lasts until you are using software that depends on a more modern version of rustc, just like any dependency. Then you upgrade it - which just like any dependency with backwards compatibility - is painless (and in fact entirely transparent if you use tooling like rustup).