Young people still have to pay a huge percentage out of their monthly wage on rent or mortgage. I remember reading that in Norway you can contract a 90+-year mortgage, that's basically putting you and your kids and grand-kids into servitude.
You are probably thinking of Sweden. I have heard it is actually more now, like 200 years (the article says 140 years). Maybe even excluding the mortgage of the co-op. People are essentially renting from the banks, without any means to default. Apparently they have capped it at 105 years now for new mortgages. (People were actually a bit upset).
In the UK there's such a thing as an "interest-only mortgage" where you don't pay down the principal at all! Which of course means lower monthly payments.
The theory is, if your mortgage interest rate was X% but some other investment like the stock market had much higher returns, a sophisticated investor might want to take the money they would have spent on repaying the principal and instead put it into that better-performing investment, then after 20 years pay off the mortgage principal with said investment.
Post-financial-crisis rules were put in place that mean banks actually have to ensure you're _making_ that higher-performing investment.