They actually covered the hardwood floors with linoleum to protect it from scratches and thus have a higher resale value (with the intent of removing it before putting it on the market), but everyone did it and when it got ugly you just replaced it - was a cheap way to renovate your house in a lot of options. So everyone just... kept the linoleum. Linoleum became a became a thing, and instead of the real hardwood floors people just used linoleum.
OK BOOMER!