Very useful thread, https://SITE/latest.rss?order=created in particular is important for the common use case of “follow a discourse’s topics in my feed reader with stable ordering”.
(I’m assuming without order=created, order would get mixed up based on reply activity. But now that I come to think of it, I watch https://discourse.haskell.org/latest.rss with bazqux.com and have never noticed a problem.)
But I see it now. If you subscribe to one of these feeds without ?order=created, it will seem fine at first but as the order of items changes the feedreader and you will get horribly confused.