The justification will, of course, be that the other options break digraph support on some ancient platform that has no public spec and will never sunset - likely one IBM AS/400 in a basement with a 45 year uptime.

Out of "respect for existing deployments," the syntax must accommodate the relic even though no one has seen it outside of the folklore of one 1993 Usenet post.

Every tool chain will begrudgingly implement it and then years later when someone proposes removing it the counter argument will be, "we can't remove it now someone is using it!" The someone, of course, is a hobbyist on the mailing list whose project depends critically in the feature.