In some parallel universe, the RSS is tightly integrated with browser and main way to "subscribe" to site's updates
RSS has two polling speeds: too fast and too slow and it can even be both at the same time.
Nostr works on a similar basis but you push to the aggregator instead of them pulling.
It costs me 10 cents/(month*feed) for superfeedr to ingest an RSS feed; it fills up an SQS queue with content items which is a model I find easy because I can drain that queue at my leisure.
It would be very cost effective for me to add a Planet and have my recommender system discover articles I like from it, that is, I'm happy to ingest 1000s of items a day to my reader.
What was good was when they had discovery. The RSS button would show up in the menu bar and you could click it and add to your RSS reader.