Surely you know the history to which the previous poster is referring? YC exists because pg and others build a company in Lisp and sold it for millions. They were a small team so they chose Lisp exactly because it helped them stay nimble.
They chose Lisp because they were comfortable with it - nimble is a social trait, not a language feature.
It's not like Lisp automatically makes everything successful - the market-trailing HN performance and UI iteration times are a strong argument that technical factors frequently do not determine success.
