What’s wrong with five over ones?

If you want the long answer.

But the short answer is that they're hugely reliant on fossil fuels, both in construction and in the way they dedicate an enormous amount of space to car parking. They're also not particularly well-built, which means you end up knocking them down and rebuilding every twenty years or so. A more traditional design of steel and concrete could last 50-100 years, but would cost more upfront to build (and builder hate that). Finally, there's the financialization of 5-over-1s, which ties their existence/maintenance to the fickle lending markets and can create exploding rents during periods of high lending costs.

They're definitely better-ish than traditional ticky-tacky ranch style homes or detached houses. But they don't make good permanent housing, because they're shoddily constructed. And they don't bring down the cost of living, because they're so heavily pegged to the current lending rates. And they really don't help with climate change, despite giving the superficial appearance of dense urban development we'd assume would reduce reliance on cars and encourage biking/walking/mass transit.