Going back to the original point, we're actually talking about slightly different things: you're talking about audience retention (making sure that someone come

Going back to the original point, we're actually talking about slightly different things: you're talking about audience retention (making sure that someone comes back), not discoverability (making sure they find you in the first place). Neither an RSS feed nor a subscribe link enable people to find you in the first place. They do, however, make it more likely that they'll come back after finding you. You should absolutely also build retention techniques into your Medium posts. And your custom blog. And anywhere else where you care about people reading your content, and keeping on reading it.