This type of architecture is the literal definition of green washing. It’s just a concrete tower with incredibly difficult to maintain trees. (Probably next to a 6 lane arterial road.)
Good question. Adding trees and other forms of applied solarpunk to concrete "buildings that have already been built" is different than prefabricated green skyscrapers which would surely be greenwashing. Images like the one in the article can be valuable to introduce new people to solarpunk ideas and positive visions of the future.
It is not stupid, it is removed. Tree roots, with time, will dig through/break concrete. Unless the trees are heavily hindered from the get go. Either way it will lead to leaks unless heavily controlled since even small roots with enough time can damage the building structure if allowed. This is a well known issue and not one you want 20 stories up at this scale.
The soil will lose nutrients, so unless everyone there how to compost constantly, then fertilisers will be needed to keep them alive, do you want that in your balcony?
The whole notion of doing this is outright irresponsible from an architecture and lifestyle perspective outside saying, "Look it has green on it, and hoping people are stupid enough to fall for it.