That's because home ownership in the US is (was?) really the primary path for the middle class to accumulate wealth. The US home mortgage as a financial instrum

That's because home ownership in the US is (was?) really the primary path for the middle class to accumulate wealth. The US home mortgage as a financial instrument is phenomenal for this. So, it was generally expected that most people would rent until they can afford to buy on their path to accumulating wealth. There are certainly reasons for people not to buy, but not being able to afford a home is more of a problem now than it has been historically (obviously). This has significant knock-on effects for individuals and the broader economy.