Gradle can do the caching of tasks itself in a level of granularity no CI can. If you keep your build cache "live" in the CI, Gradle knows to only recompile what has changed, and to only run tests which changed (or tests something which changed). I am not sure if many other build systems do that, but this is something I would absolutely expect from the build system, not CI. Do you not expect caching when building locally??

The whole idea with CI doing this is wrong IMO. All I want CI to do is call a couple of commands after setting up the environment (which would include the Gradle cache or whatever to speed up things - no need for your revolutionary CI build system).