That's already how Rust works. The post is referring to specific packages, not the whole resolution system; it is specifically 0.x versions that are incompatibl

That's already how Rust works. The post is referring to specific packages, not the whole resolution system; it is specifically 0.x versions that are incompatible at the minor revision. It is absolutely not the case that all the online tools and guides tell you to nail it down to one particular version - I have literally never seen a guide that told you to use =version notation. Finally, there's no difference between this and what you described as the Perl behavior: in both Perl and Rust, old packages with old dependencies still build.