It's in the Zeitgeist because people are coming to understand how monumentally stupid it is to continue operating in this horrific way - both in terms of overall efficiency and in terms of human suffering.
The proof that hierarchical systems do scale is in the military. They operate in absolute hierarchical fashion. In the past they did so with very limited communication, with headcounts unimaginable in today's organizations.
Pointing in the vague direction of an exemplar system and describing it a positive argument does not constitute an argument.
Neither does saying "hierarchies do not scale well", or "no they don't", without providing any evidence. So at least you are both "arguing" on the same level: unsubstantiated opinion.
Distributed is what you want to have for a) robustness (because redundancy means the work can be redirected to agents that are still alive) and b) adaptability (because system can restructure itself locally without the need to coordinate with the entirety of it).
Of course you want to apply those two recursively, e.g. hierarchies that encompass many peers at each level, etc., but that doesn't change the point. Frankly, the whole field of distributed computing is one big proof that hierarchies are good and desirable.
Ahem. Ever hear of DNS?