You can though. GHA and Gitlab CI and all the others have a large feature set for orchestration (build matrices, triggers,etc.) that are hard to test on a local setup. Sometimes they interfere with the build because of flags, or the build fails because it got orchestrated on a different machine, or a package is missing, or the cache key was misconfigured, etc.

There are a bunch of failures of a build that have nothing to do with how your build itself works. Asking teams to rebuild all that orchestration logic into their builds is madness. We shouldn’t ask teams to have to replicate tests for features that are in the CI they use.