Google Reader disappearing certainly had an impact, but I think there is another factor that contributed to companies abandoning RSS: user tracking & advertisin

Google Reader disappearing certainly had an impact, but I think there is another factor that contributed to companies abandoning RSS: user tracking & advertising. For example: our country's version of eBay used to have a great RSS service where you could set up a feed for search queries on their site. I would skim through all the feeds once a day to see if there where any deals I liked. But now they have replaced it with an email service, which requires me to visit their website to see the results of the queries (every query also has it's own notification email). Which means they get data on the things I am potentially buying and how engaged I'm with them (since the email is coupled to my account, the RSS was not). It would also give them an opportunity to present some ads, because I have to visit their site every time I want to see if there are any interesting results.