Why HttpMsg manual locking instead of refcounting

Why is HttpReply/Request (HttpMsg subclasses) using manual reference
counting by HTTPMSGLOCK/UNLOCK macros instead of automatic reference
counting by RefCount?

I find this design quite error prone, especially considering that
several of the LOCK/UNLOCK pairs is crossing code boundaries. One
glaring one is ACLCheckList->reply, assigned by the caller and freed by
the acl processing.. (why this is assigned by the caller is another
mystery, but separate).

I remember discussing this before with Duane I think, but no clear
memory of the outcome, but I think it was just confusion about how the
RefCount template works..

Regards
Henrik