A fundamental shift has occurred over the past two years in the way people consume content on the Internet. Not quite six years ago, Google bought the RSS service Feedburner for $100M and integrated it with their blogging platform, Blogger, as well as allowing bloggers on other platforms like WordPress to syndicate their content through it.
According to Compete, Feedburner is on a downward trend in terms of traffic:
BuiltWith seems to corroborate this:
In fact, Google seems to think that RSS is dying because they have deprecated the Feedburner API and are even talking about shutting it down completely in 2013. That should signal something to marketers if Google does not think the product worth keeping alive, even if simply because Google is the big player on the Internet and holds the ability to shift mindsets and kill verticals if they wish.