What had Google Reader that was amazing and no RSS existing today has is feed history: when you added a blog to Google Reader you could traverse the feed as if you added it from the beginning of the blog (intersection with the born of Google Reader).
BTW, I wrote something along the topic above in an article from 2011 [1].
I forgot that and you're totally right. It was awesome to scroll (and search!) through a feed's entire history. Ugh it makes me so mad Google got rid of all that for nothing.
At the time they shut down Listen, some podcasts (e.g. Car Talk) were closing their back episodes and charging money for them; I figured that's why Google decided to stop the service.
Did Listen not support password protected feeds? I remember a solid 2-3 years after Listen was killed (2012-2015) where Android had no passable podcast player.
BTW, I wrote something along the topic above in an article from 2011 [1].
[1] Extraction of Main Text Content Using the Google Reader NoAPI: http://blog.databigbang.com/extraction-of-main-text-content/