I was buying a house in ~2006, and they somehow got me qualified to afford the new house even if I hadn't yet sold the condo I already owned, so that the offer on the new house wouldn't be contingent on the sale of the condo. There was no way in hell I could afford both. I didn't have much of a down payment, beyond the equity in the condo. But I benefited from the insanity in that it allowed me to put in an offer without the contingency. I wondered how they were able to make it work, when I knew it definitely wouldn't. I'm sure it wouldn't happen today.
In the end, I sold the condo before I bought the house, and I've made every payment on the house on time, no problem, no bailout needed.