RSS is a feed that users control the content, arrangement, and monetization of (the creator can still monetize the content but not the feed itself).

It is “dead” because Facebook, Instagram, Google etc… can make more money if they control the content. In theory these services could add value through curation and presentation but they tend to suck donkey balls in this regard. RSS has been minimized so that the walled gardens can be shittier without losing revenue.

So yea, RSS is a fucking amazing piece of technology that is a no-brainer if you know it exists.