alt Hacker NewsLisp allows for some really, really complex and spaghetti code bases. I have seen the ultimate macro-hell from top to bottom. I know syntax does not matter, but i just cant honestly say i read lisp code as clear as something like Go. I guess it boils down to style. I have seen 100 lisp styles, and only one Go style.
Lisp is a sharp tool and I think it struggles to scale with large organisations. You would need incredible tech leadership and a very considered org structure and architecture for it to work.
Culturally, I feel a place like Valve could make it work but you could turn around and ask why does an org need to be in service to and arrange itself around a tool.