Pocket became annoying because Mozilla started shoving it down your throat, whether or not you wanted it. To most FF users, Pocket is (at very best) a source of occasional popups and other UI annoyances. People who had a use for it really liked it, though.

I used Pocket for about 3 years, before and after the acquisition. When Firefox started syncing bookmarks across devices, and they added the reader mode, Pocket became obsolete in my mind. I stopped using it because I didn't need it anymore.