We know how to package functions and data structures in modular, reusable ways; we don't know how to do that with macros, so macros hurt code reuse.
-- who's "we"? But the post itself is interesting evidence for what one could call Graham's Thesis, the idea that any programming language as powerful as Lisp is isomorphic to Lisp; or that all programming languages can be defined by the subset of Lisp that they exclude. The author argues that this exclusion is necessary and good because it gives a language a distinctive character around which a set of idioms, and therefore a community, can develop more easily.
While I totally agree with Kenny that the author's claims about Lisp have a ring of inexperience to them, I do think that this social/communal prism is an interesting one and that Lisp has some distinctive qualities in this area as in others.
How many thousand lines of Lisp have you coded? What did your biggest Lisp application do? Or were you just guessing at what it is like to program large applications in Lisp and in team situations?