You might with more justification claim that varargs methods are a code smell, as they conflate the algebraic structure of the elements and the operations on them (for example that they form a semigroup with respect to the operation at hand) with the traversal over a collection of elements, thereby grossly violationg the principle of separation of concerns. After all, many interesting algebraic structures are defined in terms of binary operators. If you separate operations between elements and traversal over collections, you can fold any operation over any traversable entity, with just #operations + #traversables functions, instead of #operations * #traversables functions. (You have a similar structure in languages from the APL family, where operators are all unary or binary, and traversal is specified by adverbs to the operators.)

This does of course not apply if you use a deliberately restricted language that has just one type of collection traversal, in that case you are better off with varargs, as n*1 < n+1.