Why doesn't defn also implicitly name the anonymous function it defines for recursion?

Question

Why doesn't defn implicitly name the function to create a named recursion point?

(clojure.walk/macroexpand-all

  '(defn foo [x]
 (foo x)))

; =>
(def foo
(fn*

([x]
 (foo x))))

This could instead expand to

(def foo

  (fn* foo ; note the foo here
([x]
 (foo x))))

which should, in case of the recursive call, compile to a direct call to the function object without the need to dereference the var at runtime.