Real estate is the messy underbelly of capitalism. Since only debt (= mortgages) creates money (and growth) you have to cut them some slack. The economy won't work if you're asking too many questions.
Mortgages aren’t only one among many phyla of dollar-denominated debt, they‘re not even the biggest [1][2]. And fiscal spending can create new money without debt. Debt is the monetary channel’s mechanism.
[1] https://www.statista.com/statistics/274636/combined-sum-of-a...
[2] https://en.m.wikipedia.org/wiki/National_debt_of_the_United_...