CL most assuredly includes vectors and hash tables in its core language spec (not to mention multidimensional arrays). And hash tables are one form of what Clojure calls a map. (The other forms exist in Common Lisp too; they're just called different things.)
http://www.lispworks.com/documentation/HyperSpec/Body/t_vect...
http://www.lispworks.com/documentation/HyperSpec/Body/18_.ht...
The author may be assuming that because CL does not use the '[]' and '{}' delimiters, CL doesn't implement the things that Clojure uses '[]' and '{}' for. If so, that assumption is wrong.
If the author finds that the use of '[]' and '{}' make code more readable, that's a matter of opinion. It would take about 6 total lines of code to teach CL to read '[]' and '{}' as a vector or a hash-table if one so desired. And yet over several decades of programming in Common Lisp, I have yet to see a program where a programmer did that. That tells me that working Common Lisp programmers have no difficulty with vectors or hash-tables absent special delimiters.
