There was the perception that RSS meant that user browsing habits couldn't be tracked. A feed reader would pull a feed but there was no way for them to know what posts people were reading and which posts they were skipping. It was a revenue sink. The push has always been for greater and greater granularity of what users were interacting with and for how long.

I've often wondered if the interim push for RSS feeds to only have the first couple of sentences of a longer post (forcing the reader to click on the link to the full article) was an attempt to mitigate this on somebody's part, he never mentioned anything like that (it was my own observation).