Whenever methods on a multifn need to be installed within a closure (usually to support lifecycle management) using defmethod can be a bit cumbersome and forces having all
method bodies within the closure.
Two cases strike me as most relevant:
If you need a method to capture bindings, it would involve creating a bound-fn and calling that from the defmethod.
With dependency injection framework, you most likely method installation when dependencies are available, making calling defmethod cumbersome.
I attached an example in foo.clj to try to make things clearer and a naive patch.
After discussing things on #clojure-dev with @alexmiller, it seems it would be feasible to add an
add-method function and to have
defmethod use that.