Comment by bsnnkv
The issue is that it's not possible to separate feeds from items. Even if some feeds are largely unread, I subscribed to them because I liked something they posted on a specific topic, and I still want to get updates whenever there is another feed item related to that specific topic. Ultimately the "feed" is the mechanism of delivery, but I don't think it should be the primary mode of categorizing item consumption.
I've worked on this issue a little in a different context, where you can follow posts from people on Bluesky related to specific topics, and this is ideally what I would like to be able to do more of with RSS.[1]