While CC0 is beneficial in some ways, it also has some disadvantages. The lack of an attribution requirement may seem convenient, but it can also cause confusion in the standards community. For example, there are derivative specifications ("forks") that are not prominently identified as copies of WHATWG standards. Such unattributed forks create confusion both about the origin of the standard and about any applicable intellectual property rights (IPR) commitments. Use of the CC BY license makes it easier for implementers to trace what they are implementing back to the original source and its accompanying IPR commitments.
Звучит так, словно они внезапно решили взбугуртнуть от W3C'шной копии их стандарта. Раньше же нормально было. Или кто-то ещё покопировал? Странные люди.