I read the RSS feed docs (no Atom?), & I don’t see any query parameters about this. One option I would really like to see is ?muted_users=foo,bar or getting a feed only available to my user account (RSS with auth header).
I’m subscribed to one particular Discourse & while a lot of content is useful/relevant there is a particular user I would like to not see because they spam too many questions (ones I think would be better asked in IRC, similar). With vague titles, it’s hard to know that this user is the postmaker.
As an alternative, my feedreader, Miniflux, allows blocking via titles, but this would require that the postmaker’s ID be listed in the title, but I would be better off opening an issue with the feedreader to allow blocking based in additional identifiers. Edit: open issue.