This is the key. I think sending any unsolicited traffic to 3rd party websites counts as violating my privacy. Pocket goes far beyond that.
Pocket Recommendations are personalized based on your browsing behavior in Firefox. It doesn't matter that Mozilla and Pocket don't see your browsing history directly. While the choice of which links to push at you are made client side if Pocket knows which pages are suggested to you (either as they are pushed to your browser or after you've clicked them) then they can take away from that information about why you were targeted for those sites.
Sure enough, Pocket collects stats on which links show up in your browser and whether or not you click on them.
"Sponsored stories" often link to DoubleClick or Bitly who redirect you to the suggested site so those companies are also collecting your data because of Pocket. Handing data to DoubleClick is not protecting user's privacy.
Even if you opt out of data collection in Firefox's preferences Pocket and Mozilla will continue to serve you personalized sites and will continue to collect data on you and your browsing history.
I don't mind that pocket exists, but it shouldn't be enabled by default, and it shouldn't take going into about:config to disable.
Firefox should be applauded for taking steps to try to make money off their user's personal information without selling it outright, but at the end of the day they are still trying to make money off their user's personal information.
They do have to compete with Google, but they can best do that by providing a better experience for users and by protecting their privacy.
I've been a long time user of firefox because it's still the best browser when it comes to privacy and control, but it takes an increasing number of default setting changes and about:config edits to get it to stop leaking my data to 3rd parties. It's already to the point where I can't just recommend it to others without explaining there are a ton of settings they should immediately disable or change to protect themselves.