It's still OO, it's just not the style most people are familiar with. One can implement multimethhods in Java and C++, it's just cumbersome. (In fact, Stroustrup has said he wanted C++ to be able to do multiple dispatch at the language level, but he never found an expression and implementation that satisfied him in terms of performance and the type system.)

CLOS has had multimethods for years, and that is indeed OO.