I don't see how that follows. Declarative build configuration is very good and Rust needs to lean harder in that direction and minimize the use of build.rs.
The best way is to keep scripting out of build files. Build recipes must be simple, boring, reliable, and same everywhere.
Gradle and SBT allow unlimited scripting and builds often end up as an unreliable mess. The more cleverness they put into the build definition, the more frustrating it is to use in practice.
