I know there was some controversy when Firefox integrated (and then acquired) Pocket, but I don't quite understand why people were so upset. My understanding (from having talked with folks at Mozilla) is that the suggested stories are personalized on the client side—so any info used to customize the stories for you isn't flowing back to Mozilla. Instead, they deliver a bunch of stories to the client, then the client sorts out which ones will be recommended. From a privacy perspective, this seems like a good way to do things. And I personally find the suggested stories to be interesting sometimes, and never creepy/inappropriate.

Regardless, it's good to know this can be turned off.