I don't think anyone considers multidispatch to be an anti-pattern. Here's Guido himself emulating multimethods in Python via decorators: http://www.artima.com/weblogs/viewpost.jsp?thread=101605

They're certainly a bit obscure though. Julia is the only new language that I'm aware of that prominently features multiple dispatch as a first-class language feature: http://julia.readthedocs.org/en/latest/manual/methods/