I read the LSOFT page describing the DMARC aliases, and it seems like there is a good technical reason for doing so. To disallow the LISTSERV-supplied DMARC aliases would prevent some participant's mail from being delivered (or would have it downgraded to "junk" status by the receiving mail agent).
Regarding the use of aliases in general, there are good reasons to use them (as have been described in other messages in this thread). The use of an alias is a signal of a sort, and readers can take that signal into account as they read and consider the content of the message. I wouldn't want to see aliases banned from the list. I think it is also a health practice to encourage the use of email signatures whenever possible so community members get to know each other.
Open Source Community Advocate
Index Data, LLC
On Jul 12, 2019, 11:07 AM -0400, Eric Lease Morgan <[log in to unmask]>, wrote:
> With the advent of some sort of new SMTP enhancement called DMARC, it is possible to post to LISTSERV applications (like ours) and have your email address obfuscated, like above. This is apparently a feature.  Yes, direct replies to an address like [log in to unmask] do make it back to the original sender, but without some sort of signature can be very difficult to know to whom one is replying.
> I think any poster to the mailing ought to be easily identifiable. One ought to be able to easily know the name of the poster, their affiliation, and their email address. Such makes things: 1) more transparent, and 2) lends credibility to the post. Even if I don't sign this message you can see that my name is Eric Morgan, I work for Notre Dame, and my address is [log in to unmask] The posting above works because there is/was a full signature. Postings from [log in to unmask] are difficult to swallow but I can live with them. But postings from EM <[log in to unmask]> with no signature I think are not respectful. Remember, "On the Internet, nobody knows you are a dog." 
>  dmarc - https://www.lsoft.com/news/dmarc-issue1-2018.asp
>  dog - https://en.wikipedia.org/wiki/On_the_Internet,_nobody_knows_you're_a_dog