“Because green skyscrapers and high-rises are a bullshit non-solution to serious systemic problems.”
“But if you want greenery on a building nonetheless, do I have an idea for you – a portable, modular, scalable solution called ‘potted plants on your balcony’.”
The downside is almost certainly structural (significant weight as well as moisture, and a need for long term structural integrity and safety, likely don’t pair well. Especially not when the people doing the building are looking for cost effectiveness).
If you don’t build with cardboard this problem is very easy to solve, its called putting a goddam Pond liner between the dirt and the structure itself.
And the weigh isn’t a issue with low buildings, say 10 to 20 floor that aren’t made from cardboard, and higher than that is inefficient in all regards anyway and should be avoided.