delayed-warnings-hook versus deferred-action-function

[Glenn Morris]

In 24.1, deferred-action-function has been deprecated in favour of just
using post-command-hook. Fair enough, the former was never really used
for anything.

However, delayed-warnings-hook has been added, and, although it has a
more clearly documented purpose, seems to be functionally equivalent to
the deprecated interface. Eg from command_loop_1:

      if (!NILP (Vdelayed_warnings_list))
        safe_run_hooks (Qdelayed_warnings_hook);

      if (!NILP (Vdeferred_action_list))
        safe_run_hooks (Qdeferred_action_function);

Aren't these two changes inconsistent? Why couldn't an element just be
added to post-command-hook to process delayed-warnings?