Oh, what a twist!
In a story that began two years ago with Pocket's integration by Mozilla [1] in Firefox [2], large segments of the userbase spoke out with scathing criticism.
This, at first blush, appears unrelated: Mozilla previously announced its Context Graph initiative, which was a bold undertaking to be built partially upon a new and emerging set of W3C standards to take back some of the control over linkage, metadata, and the consumption and annotation of web content [3] from big incumbent providers who run content portals, content silos, or content aggregators (largely the usual suspects, including Google, Facebook [4], Apple, Microsoft, and Yahoo [5]).
To understand this play, temporarily forget about Mozilla the Foundation, and think about Mozilla as a strategic competitor to the above. In the case of Pocket, a hard-to-deny side effect is that Pocket's presence in Firefox, despite the exact nature of the integration, is likely here to stay. While this is bound to frustrate many, Mozilla's competitors routinely ship software or entire platforms with tight captive integrations, against which competition has proven difficult to mount solely on the merits of values and philosophical purity.
[1] https://hn.algolia.com/?query=firefox%20pocket
[2] https://hn.algolia.com/?query=mozilla%20pocket
[3] https://news.ycombinator.com/item?id=13729525#13740110
[4] https://news.ycombinator.com/item?id=13375451#13375917
[5] https://news.ycombinator.com/item?id=12863565#12867493