The example code in the article also makes use of objects such as std::string, sets etc.
I actually happen to like iostream, for the reasons of it being standard and extendible; just don't expect any particular performance out of it.
That said, I don't disagree that C++ can support functional programming. I would just argue there are languages better suited for this.
(edited for clarity)
The STL is mainly a generic library, not an OO library.
http://www.stlport.org/resources/StepanovUSA.html
I actually happen to like iostream, for the reasons of it being standard and extendible; just don't expect any particular performance out of it.