A better question: "What impressive programs are written in Lisp?". Or "Why isn't there a Squeak-like Lisp machine environment, where 'compatibility' doesn't have to matter?". If a language is incredibly productive and programmable, why don't we already have a VPRI-like STEPS environment in 20,000 lines?
I'd only call this anecdote, but one or more benchmarks assert that cl-ppcre, common lisp's perl-compatible regex implementation, is faster than any other, include perl's.
The larger question I'm intuiting from your post, "Why doesn't language power make a difference in practice?" I don't have an answer to.
> Why doesn't language power make a difference in practice?
Depends on your definition of "make a difference in practice". If you mean "make the language become one of the dominant ones", yeah, that doesn't seem to have happened. Either Lisp is less effective in the large than one would expect from its power, or it's less powerful in practice than people think, or power has almost no relation to language dominance.
But if you mean "make a difference to the user", well, it lets the user more easily write the program that the user wants to write. In practice, that makes a difference - to that user.
This is covered in the article. You might say it's the central point of the article - lisp attracts "lone wolf" programmers who want to build perfect abstractions closely mapped to the real-world problem; as opposed to projects that require many man-years of effort run by MBA's who want fungible "resources" to do their tiny-bite-sized pieces according to spec. The philosophy is different.
http://www.vpri.org/pdf/tr2011004_steps11.pdf