Aside from the “where you build isn’t where you run problem”, there’s the “this syscall doesn’t work when running on filesystem X or accessing /dev/urandom”.
Not only is the autoconf solution not fixing the problem, it’s placing a massive undue burden on developers. Linus has been inconsistent here. Telemetry would have been helpful here in aiding this work (ie support it with the slow path but report the event so that distro maintainers could provide feedback on broken paths). Once you think you’ve eliminated the long tail of issues, then remove and see if anything remains broken that telemetry didn’t catch.
It would break if compiled on old kernel and run on new kernel. When CI is containerized the kernel might not even have anything to do with the distro that you're building on.
