Yes, you are correct, I'm not arguing every single mortgage will end in default, but that every macro environment where zero down mortgages proliferate will always end in tears to whoever is left holding the bag (currently homeowners and investors, and, crucially, rarely loan originators).

Of course, to my knowledge, the only environment where zero down mortgages were really widespread was the mid-aughts housing bubble, but even with an n of 1 I still think it's a bad omen.