(0) (the quote) is not in contradiction with (1) and (2). It is (1), a break from the situation implied in (0), that necessitates (2).
If all the contributors own their part and license it under the GPL, this ensures a level playing field. The GPL provides a shield for all involved. If they all assign copyright to a single entity, they lose their shield and this entity has the advantage. This is why that entity should provide something in return: a GPL-like guarantee.
If all the contributors own their part and license it under the GPL, this ensures a level playing field. The GPL provides a shield for all involved. If they all assign copyright to a single entity, they lose their shield and this entity has the advantage. This is why that entity should provide something in return: a GPL-like guarantee.