Ah ha! Just as in Am I the only non-sysop here? - #33 by Moin, it turns out
is the single remaining connection that users use to finally figure out they are using Discourse!
I.e., no matter how hard the Discourse authors try to not reveal to the ultimate end user what software package they are actually using, it seems users are still able via this link to figure it out!
(But of course that is if they paid attention to the welcome message, or looked for it in their mailbox years later when they were curious about what they were using.)