Because I use it every day. I use NetNewsWire to read new posts. I subscribe to a bunch of newsletters hosted on Substack—you can just type /feed after the URL and you’ll receive Substack through RSS. You can do the same with Medium.
For other newsletters, I use Kill the Newsletter to subscribe via RSS. I subscribe to some of them via email as well, in order to reply to the writers.
It’s surprising to me how energizing reading like this feels. It also feels familiar. I highly recommend it.