home ownership is directly tied to rental affordability, as the rental market is always going to be the alternative. Even if people aren't perfectly rational agents, everyone has their own subjective present value function or heuristic to compare the cost of owning vs renting. They may be separate forms of tenure, but they do in fact compete with one another on price/value. If the price of alternatives to ownership were to fall, the price homebuyers are willing to pay would also fall.

> [multifamily housing units are] not really the kind of place that most people want to buy to live in

this is a descriptive norm - observed or perceived behaviors, preferences, and trends among a group of people who, typically, don't really have a choice to buy anything other than a detached house. Family-sized condos are actually highly sought after in dense urban areas where a detached house is an overt luxury, while in suburbs and rural areas they're a rare choice simply because it's illegal to build them.