Honestly, that’s just bullshit. Every language is more productive with fewer developers since communication does have an inherent cost. But there is no Silver bullets as per the famous article, no language provides not even 2fold increase in productivity over another managed one, let alone an order.

while I agree a 500 fold increase is a bit of exaggeration, There is some merit to the argument.

more expressive languages including common lisp certainly give more power for an experienced engineer to outperform someone fresh out of univeristy. enough to say that I'd rather have 2-3 senior engineers experienced with common lisp or clojure or haskell over 10-15 juniors working on go or python.

and what if you gave them the same expressive language? I'd argue that its even more dangerous. Common lisp is a powerful language but its easy to code yorself into a corner if you don't have the experience to properly use it. it;d be easy to build overcomplicated systems that are brittle. go is in fact better for them because it limits the damage they can cause.