My point was that we have very good reasons to want to design DNS records relating to HELO authorization, equally good reasons to want DNS records relating to RFC2821-MAIL-FROM, and good, though different, reasons to want RFC2822 authorization info. They don't need to be the same reason.
First of all, with HELO we want to establish a chain of trust for debugging purposes, and for allowing bounce messages to find their way to the originator of a message if the message is rejected later in the chain. With additional (out of our scope) reputation services, HELO authorization could enable a number of features, _some_ of which we can imagine today.
Next, with RFC2821-MAIL-FROM we want to have a useful bounce address, so that failure information can _automatically_ pass to a person able to do something about it.
Third, with the RFC2822 headers, we want _some_ domains to be able to signal to recipients whether the email they receive is consistent with the practices of that domain for sending email. Not every domain will want this service, but it can be a big win for those that want it.
Thus, three different things we're trying to accomplish, for three different "good reasons".