The point is not so much the size (which has changed over the years) but how foundational it is. You can remove without replacement almost everything else from

The point is not so much the size (which has changed over the years) but how foundational it is. You can remove without replacement almost everything else from that pie chart except Linux and GNU and still have a functional OS, but without any coreutils or Linux or a replacement for either you don't have much of an OS left.